2AEKH-M18IMAXMobile Headphone Amplifier with DAC

Questyle's flagship mobile DAC with headphone amplifier, M18i Max, redefines the new standard for flagship devices in the mobile Hi-Fi audio industry with its hardcore performance and industrial aesthetic design. Equipped with efficient fast-charging technology and an intelligent power management system, its 1800mAh lithium battery offers up to 10 hours of extended battery life, and also supports listening while charging, ensuring users can enjoy a high-fidelity music experience throughout the day. M18i Max supports switching between USB DAC and dual-mode lossless Bluetooth, catering to listening needs in both wired and wireless scenarios. M18i Max contains two self-developed Current Mode PCT patent amplifier SiP modules, each housing four amplifier units, balancing powerful drive with delicate tonality. It features the flagship ESS Combo DAC ES9219Q in a dual DAC mono design, paired with a TTA (Three-Tier Architecture) decoding framework comparable to desktop devices, challenging the limits of portable audio quality again . Bauhaus design language is perfectly integrated with a high-definition OLED screen, and it also supports HD calls. M18i Max is Apple MFi certified, meeting Apple's strict requirements for power consumption and compatibility of external devices. Flagship Mobile with DAC Headphone Amplifier Power On/Off • Hold the power button for 2 seconds to power on and enter the selected input mode. • Hold the power button for 2 seconds to power off. Gain & USB Mode Selection Bluetooth Mode • In Phone/PC mode, short-press to switch gain (HIGH/LOW) for different headphones. • Long-press (3s) to switch USB mode (1.0/2.0). • Reconnect USB cable after switching modes. • Hold the MFB button for 2 seconds to pair or reconnect. • Press to play/pause; double-click to skip tracks. • For calls: click to answer, double-click to reject; click to hang up. GAIN/MFB button Volume - Volume + Bluetooth Mode PC Mode Phone Mode Microphone Power Button USB audio input 3.5mm Single-ended Headphone Jack 4.4mm Balanced Headphone Jack Type-C USB Charging Port M18i Max USB 2.0 Mode Supports Win XP/Vista/Win7-Win11, Linux, Android, HarmonyOS, macOS, and iOS systems. For Windows first-time use, download the USB driver from the Questyle official website (www.questyle.com) to enable the DAC function. macOS is driver-free; simply select the corresponding sound card output. Supports up to 384kHz/32bit and DSD256. When Used as a USB DAC M18i Max USB 1.0 Mode No driver installation is required on the PC; it's plug-and-play, supporting up to 96kHz/24bit. It is recommended to set the PC system volume to maximum and control the volume via M18i Max. To adapt to multiple scenarios and meet flexible pairing needs, M18i Max USB offers two decoding modes. Volume Indicator 384000 USB 2.0PCM Sampling Rate Power Indicator Phone/PC USB InputUAC ModeDecoding Format GainIndicator Output Device Charging Indicator Driver Installation 96kHz | 24bit 48kHz | 24bit 44.1kHz | 16bit 48kHz | 24bit When Used as a Bluetooth DAC 48kHz | 24bit Bluetooth Mode Display Sample Rate | Bit RateCodec Format M18i Max is equipped with Qualcomm Snapdragon Sound™ technology and is certified for both Snapdragon Sound and Sony LDAC. With Bluetooth 5.4, it supports Qualcomm's lossless aptX Adaptive, aptX HD, aptX codecs, as well as Sony's LDAC 96kHz/24bit codec and the latest LE Audio codec. It also supports mainstream AAC and SBC codecs. Intelligent Charging & Energy Management System Phone Mode • The audio USB port only transmits data and does not draw power; M18i Max is powered by its own battery. • Both Bluetooth and Phone modes use battery power. PC Mode • The audio USB port transmits data and can also power the system and charge the battery. • In PC mode, if the USB host device current is limited, M18i Max automatically adjusts the battery charging current based on system load, prioritizing the power needs of the main system before intelligently regulating the battery charging current. • When connected to a phone in PC mode, it will consume the phone's battery. Energy Management System • In PC mode with both USB ports connected, M18i Max prioritizes using power from the charging port. • When a power adapter is plugged into the dedicated charging USB port, M18i Max enters charging state and supports listening while charging in any mode. Packaging & Accessories Type-C to Type-C Cable x 1 M18i Max x1 User Manual x 1 Warranty Card x 1 Type-A to Type-C Adapter x 1 This device complies with part 15 of the FCC Rules. Operation is subject to the following two conditions: (1) This device may not cause harmful interference, and (2) this device must accept any interference received, including interference that may cause undesired operation. Any changes or modifications not expressly approved by the party responsible for compliance could void the user's authority to operate the equipment. NOTE: This equipment has been tested and found to comply with the limits for a Class B digital device, pursuant to Part 15 of the FCC Rules. These limits are designed to provide reasonable protection against harmful interference in a residential installation. This equipment generates, uses and can radiate radio frequency energy and, if not installed and used in accordance with the instructions, may cause harmful interference to radio communica- tions. However, there is no guarantee that interference will not occur in a particular installation. If this equipment does cause harmful interference to radio or television reception, which can be determined by turning the equipment off and on, the user is encouraged to try to correct the interference by one or more of the following measures: -- Reorient or relocate the receiving antenna. -- Increase the separation between the equipment and receiver. -- Connect the equipment into an outlet on a circuit different from that to which the receiver is connected. -- Consult the dealer or an experienced radio/TV technician for help. The devi…

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1/1 USAgentforServiceofProcessLETTEROFATTESTATION TO: OfficeofEngineeringTechnology FederalCommunicationsCommission 7435OaklandMillsRoad Columbia,MD21046 USAgentforServiceofProcess: CompanyName:HOPEKCORPORATIONINC Address:16755CoyoteBushDrUnit84,SanDiego,CA92127UnitedStates FRN:0034562900 ContactName:YangyangXu TelephoneNo:561-875-9826 E-mail:[email protected] ThisletteristoconfirmthattheUSAgentforServiceofProcessacceptsresponsibilitytoactas alocalrepresentativeonbehalfofQuestyleAudioTechnologyCo.,Ltd TheUSAgentforServiceofProcessisawareofandagreestocomplywiththerequirements outlinedintheFCCEquipmentAuthorizationProgram,ReportandOrderFCC22-84,andclause §2.911. Applicant: CompanyName:QuestyleAudioTechnologyCo.,Ltd ProductDescription:MobileHeadphoneAmplifierwithDAC FRN:0024513806 GranteeCode:2AEKH FCCID:2AEKH-M18IMAX ContactName:Nataliewu Address:RoomNo.13A,Floor13,YunsongBuilding,Tairan8thRoad,Chegongmiao,Futian District,Shenzhen,China518040 TelephoneNo:008675582835670 E-mail:[email protected] TheApplicantisawareofandagreestocomplywiththerequirementsoutlinedintheFCC EquipmentAuthorizationProgram,ReportandOrderFCC22-84,andclause§2.911. ThisAgreementisvaliduntil(Permanentlyvalid). Date:2026/1/30 Applicant’sName: QuestyleAudioTechnologyCo.,Ltd USAgentforServiceofProcess’sName: HOPEKCORPORATIONINC Title:ProjectManagerTitle:Manager SignatureSignature

Rev 1/26/2023 Questyle Audio Technology Co., Ltd Federal Communications Commission Authorization and Evaluation Division 7435 Oakland Mills Road Columbia, MD 21046 USA Date: Jan. 27, 2026 Ref: Attestation Statements Part 2.911(d)(5)(i) Filing FCC ID: 2AEKH-M18IMAX [Questyle Audio Technology Co., Ltd] certifies that the equipment for which authorization is sought is not “covered” equipment prohibited from receiving an equipment authorization pursuant to section 2.903 of the FCC rules. [Questyle Audio Technology Co., Ltd] certifies that the equipment for which authorization is sought does not include cybersecurity or anti-virus software produced or provided by Kaspersky Lab, Inc. or any of its successors and assignees, including equipment with integrated Kaspersky Lab, Inc. (or any of its successors and assignees) cybersecurity or anti-virus software pursuant to DA-24-886 and KDB 986446 D01 Covered Equipment Guidance section B(2a). Device is inherently compliant based on hardware limitations or software controls. or A Software Bill of Materials (SBOM) is provided to the TCB for review, and The end-user or third parties cannot install additional software on this device. Sincerely, (Applicant signature) (Applicant printed name) Natalie wu Rev 1/26/2023 Questyle Audio Technology Co., Ltd Federal Communications Commission Authorization and Evaluation Division 7435 Oakland Mills Road Columbia, MD 21046 USA Date: Jan. 27, 2026 Ref: Attestation Statements Part 2.911(d)(5)(ii) Filing FCC ID: 2AEKH-M18IMAX [Questyle Audio Technology Co., Ltd] certifies that, as of the date of the filing of the application, the applicant is not identified on the Covered List (as a specifically named entity or any of its subsidiaries or affiliates) as an entity producing “covered” equipment. Sincerely, (Applicant signature) (Applicant printed name) Natalie wu

SHENZHEN ATN COMMUNICATION TECHNOLOGY CO.,LTD. Page 1 Version：A0ATN-PAS-QD-0220 SHENZHEN ATN COMMUNICATION TECHNOLOGY CO.,LTD. SPECIFICATION FOR APPROVL Questyle Audio Technology Co., Ltd M18i-MAX ATN146001 2.4~2.48GHz 1PCS CUSTOMER： CUSTOMER PRJ： CUSTOMER P/N： OUR PRJ： SPECIFICATIONS： Q’TY： DATE： 2025.12.20 C USTOMER makerreviewerApproverStructurerElectronicerApprover Address: 504-505,Summer Valley, MeishengChuanggu Science and Technology Innovation Park, Longchang Road, Xin'anStreet, Baoan District, Shenzhen. Tel：0755-29308863Fax：0755-29308861 SHENZHEN ATN COMMUNICATION TECHNOLOGY CO.,LTD. Page 3 Version：A0ATN-PAS-QD-0220 1、 Test Equipment&Conditions 1.1 Network Analyzers Agilent Technologies E5071B 1.2 ommunications Test Set CMW500 1.3 Test System 2、Product Specification 2.1 、 Material&Mechanical Characteristics FPCMaterial Antenna type PIFAANT 22°C±5°C 35-65% 2.2、Storage conditions Storage Temperature relative humidity Storage life 360 days SHENZHENATN COMMUNICATIONTECHNOLOGYCO.,LTD. Page 4 Version ：A0ATN-PAS-QD -0220 3、Matching circuit 4、Test Data Report 4.1 S11 Parameter 4.2 Gain & Efficiency 4.3 Radiationpattern Page 5 Version：A0ATN-PAS-QD-0220 SHENZHEN ATN COMMUNICATION TECHNOLOGY CO.,LTD. 4.4 OTA Test Data 5、Assembly requirements 1 6、Product Drawing Unit: mm

Questyle Audio Technology Co., Ltd Office of Engineering Technology Federal Communications Commission 7435 Oakland Mills Road Columbia, MD 21046 USA Date: January 30, 2026 Subject; Request for Confidentiality FCC ID: 2AEKH-M18IMAX To Whom It May Concern, Pursuant to the provisions of the Commission’s rules Title 47 Sections §0.457 and §0.459, we are requesting the Commission to withhold the following attachment(s) as confidential documents from public disclosure indefinitely. These documents contain detailed system and equipment descriptions and are considered as proprietary information in operation of the equipment. The public disclosure of these documents might be harmful to our company and would give competitors an unfair advantage in the market. Schematic Diagram Block Diagram Parts List Operational Description Tune-up Procedure Software Security Requirements for UNII devices In additional to above mentioned documents, in order to comply with the marketing regulations in Title 47 CFR §2.803 and the importation rules in Title 47 CFR §2.1204, while ensuring that business sensitive information remains confidential until the actual marketing of newly authorized devices, we request Short Term Confidentiality of the following attachment(s); External Photos Test Setup Photos Internal Photos User Manual For 45 days, pursuant to Public Notice DA 04-1705. OR For 180 days pursuant to KDB 726920 D01. It is our understanding that all measurement test reports, FCC ID label format and correspondence during the certification review process cannot be granted as confidential documents and this information will be available for public review once the grant of equipment authorization is issued. Sincerely, Signature: Name: Natalie wu Title: Project Manager

Effective Date: April 2, 2020 QSF 7.6.4-8 – Agent Authorization Letter Template Page 1 of 1 Revision Date: Revision: 0 Questyle Audio Technology Co., Ltd Date: Jan. 27, 2026 Product Model Number: Questyle M18i Max FCC ID: 2AEKH-M18IMAX To whom it may concern, Re: Product Certification Representative Authorization Letter We authorize QAI Laboratories Ltd. 3980 North Fraser Way, Burnaby B.C. Canada V5J 5K5 to act on our behalf on all matters concerning the above named equipment. This shall include the following:  Testing  Approval applications and procedures We declare that QAI Laboratories Ltd. is allowed to forward all information related to the approval project to the applied certification body and to the notification entities and to discuss any issues concerning the approval application. Any and all acts carried out by QAI Laboratories Ltd. on our behalf shall have the same effect as acts of our own. By: Contact Listed on FCC Wesbite Title: Project Manager Email: [email protected] Telephone: 008675582835670 On behalf of: Questyle Audio Technology Co., Ltd

Ext Photos Model: Questyle M18i Max Photo 1 Photo 2 Photo 3 Photo 4 Photo 5 Photo 6 Photo 7 Photo 8

222-262103 R-R-Sor-M18IMAXYU10452-23003 85.00 55.00 53.50 15.20 [email protected] Phone+86-755-8283-5670 www.questyle.com Room No.13A, Floor 13, Yunsong Building, The 8th Tairan Road, Futian District, Shenzhen, China 518000 Questyle Audio Technology Co.,Ltd Questyle · 旷世之声 The “Questyle · 旷世之声” are registered trademarks of Questyle Audio Technology Co., Ltd. CET PRODUCT SERVICE SP. Z O.O. Ul. Dluga 33 102 Zgierz 95-100 Polen Tel: +48791019706 Email: [email protected] CET Product Service Ltd.(for authorities only) Beacon House Stokenchurch Business Park,lbstone Rd, Stokenchurch, High Wycombe HP14 3FE UK E-MAlL:[email protected] SN · 제품명 Headphone Amplifier · 모델명 M18i Max · 인증번호 R-R-Sor-M18i Max · 제조국 중국 · 제조원 Questyle Technology Co Ltd · 제품명 전지 · 모델명 C0888A2 · 인증번호 YU10452-23003 · 제조국 중국 · 제조원 Guangdong Pow-Tech New Power Co., Ltd. · 정격전압 3.7 Vd.c., 4,300 mAh · 수입원 (주)소리샵 · A/S 전화 02-3446-7391 · 제조년월 별도표기 Designed by Questyle · Made in China Model ： M18i Max Product ： Mobile Headphone Amplifier with DAC Colour ： Black Rate Input： 5V2A 6 972007 017272 EAN 193838 755904 UPC 222-262103 FCC ID: 2AEKH-M18IMAX

Int Photos Model: Questyle M18i Max Photo 1 Photo 2 ANT Photo 3 Photo 4 Photo 5 Photo 6 Photo 7 Photo 8

- Page 1 of 9 - Report No.: HB20251225006E-03 Add:Room 102, 201, Building 2, Yuanwanggu RFID Industrial Park, Tongguan Road, Tianliao Community, Yutang Street, Guangming District, Shenzhen,China Tel: (86-755) 29989321 Fax: (86-755) 29985110 Web:www.sz-hongbiao.com RF EXPOSURE Test Report Product: Mobile Headphone Amplifier with DAC Trade Mark: Questyle Model Number: Questyle M18i Max FCC ID: 2AEKH-M18IMAX Prepared for Questyle Audio Technology Co., Ltd Room No. 13A, Floor 13, Yunsong Building, Tairan 8th Road, Chegongmiao, Futian District, Shenzhen, China 518040 Prepared by Shenzhen HongBiao Certification& Testing Co., Ltd Room 102, 201, Building 2, Yuanwanggu RFID Industrial Park, Tongguan Road, Tianliao Community, Yutang Street, Guangming District, Shenzhen, China Tel.: +86-755-2998 9321 Fax.: +86-755-2998 5110 Website: http://www.sz-hongbiao.com - Page 2 of 9 - Report No.: HB20251225006E-03 Add:Room 102, 201, Building 2, Yuanwanggu RFID Industrial Park, Tongguan Road, Tianliao Community, Yutang Street, Guangming District, Shenzhen,China Tel: (86-755) 29989321 Fax: (86-755) 29985110 Web:www.sz-hongbiao.com Table of Contents 1 GENERAL DESCRIPTION ................................................................................................................................... 5 1.1 DESCRIPTION OF EUT ................................................................................................................................................ 5 1.2 TEST MODE .............................................................................................................................................................. 5 1.3 TEST SETUP .............................................................................................................................................................. 5 1.4 ANCILLARY EQUIPMENT .............................................................................................................................................. 5 2 TEST FACILITIES AND ACCREDITATIONS ............................................................................................................ 6 2.1 TEST LABORATORY ..................................................................................................................................................... 6 2.2 ENVIRONMENTAL CONDITIONS ..................................................................................................................................... 6 2.3 MEASUREMENT UNCERTAINTY ..................................................................................................................................... 6 2.4 TEST SOFTWARE ........................................................................................................................................................ 6 3 LIST OF TEST EQUIPMENT ................................................................................................................................ 7 4 RF EXPOSURE .................................................................................................................................................. 8 4.1 STANDALONE SAR TEST EXCLUSION CONSIDERATIONS........................................................................................................ 8 4.1.1. Limit ............................................................................................................................................................ 8 4.1.2. Test Procedures ........................................................................................................................................... 8 4.1.3. Test Result ................................................................................................................................................... 9 - Page 3 of 9 - Report No.: HB20251225006E-03 Add:Room 102, 201, Building 2, Yuanwanggu RFID Industrial Park, Tongguan Road, Tianliao Community, Yutang Street, Guangming District, Shenzhen,China Tel: (86-755) 29989321 Fax: (86-755) 29985110 Web:www.sz-hongbiao.com TEST RESULT CERTIFICATION Applicant’s Name ................. : Questyle Audio Technology Co., Ltd Address ................................. : Room No. 13A, Floor 13, Yunsong Building, Tairan 8th Road, Chegongmiao, Futian District, Shenzhen, China 518040 Manufacturer's Name .......... : Questyle Audio Technology Co., Ltd Address ................................. : Room No. 13A, Floor 13, Yunsong Building, Tairan 8th Road, Chegongmiao, Futian District, Shenzhen, China 518040 Product description Product name ........................ : Mobile Headphone Amplifier with DAC Model Number ....................... : Questyle M18i Max Standards ............................. : FCC CFR 47 PART 1 , 1.1310 Test procedure ....................... : KDB 447498 D01 General RF Exposure Guidance v06 This device described above has been tested by Shenzhen HongBiao Certification& Testing Co., Ltd and the test results show that the equipment under test (EUT) is in compliance with the EMC requirements. And it is applicable only to the tested sample identified in the report. Date of Test ............................................ : Date (s) of performance of tests ............. : Dec. 25, 2025~Jan. 27, 2026 Test Result ............................................... : Pass Testing Engineer : (Zoe Su) Technical Manager : (M i n g Liu) Authorized Signatory : (L e o S u) - Page 4 of 9 - Report No.: HB20251225006E-03 Add:Room 102, 201, Building 2, Yuanwanggu RFID Industrial Park, Tongguan Road, Tianliao Community, Yutang Street, Guangming District, Shenzhen,China Tel: (86-755) 29989321 Fax: (86-755) 29985110 Web:www.sz-hongbiao.com Revision History Revised No. Date of Issue Description 01 Jan. 27, 2026 Original - Page 5 of 9 - Report No.: HB20251225006E-03 Add:Room 102, 201, Building 2, Yuanwanggu RFID Industrial Park, Tongguan Road, Tianliao Community, Yutang Street, Guangming District, Shenzhen,China Tel: (86-755) 29989321 Fax: (86-755)…

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- Page 1 of 54 - Report No.: HB20251225006E-01 Add:Room 102, 201, Building 2, Yuanwanggu RFID Industrial Park, Tongguan Road, Tianliao Community, Yutang Street, Guangming District, Shenzhen,China Tel: (86-755) 29989321 Fax: (86-755) 29985110 Web:www.sz-hongbiao.com Test Report Product: Mobile Headphone Amplifier with DAC Trade Mark: Questyle Model Number: Questyle M18i Max FCC ID: 2AEKH-M18IMAX Prepared for Questyle Audio Technology Co., Ltd Room No. 13A, Floor 13, Yunsong Building, Tairan 8th Road, Chegongmiao, Futian District, Shenzhen, China 518040 Prepared by Shenzhen HongBiao Certification& Testing Co., Ltd Room 102, 201, Building 2, Yuanwanggu RFID Industrial Park, Tongguan Road, Tianliao Community, Yutang Street, Guangming District, Shenzhen, China Tel.: +86-755-2998 9321 Fax.: +86-755-2998 5110 Website: http://www.sz-hongbiao.com - Page 2 of 54 - Report No.: HB20251225006E-01 Add:Room 102, 201, Building 2, Yuanwanggu RFID Industrial Park, Tongguan Road, Tianliao Community, Yutang Street, Guangming District, Shenzhen,China Tel: (86-755) 29989321 Fax: (86-755) 29985110 Web:www.sz-hongbiao.com Table of Contents 1 GENERAL DESCRIPTION ................................................................................................................................... 6 1.1 DESCRIPTION OF EUT ................................................................................................................................................ 6 1.2 TEST MODE .............................................................................................................................................................. 6 1.3 OPERATION CHANNEL LIST ........................................................................................................................................... 7 1.4 TEST SETUP .............................................................................................................................................................. 7 1.5 POWER SETTING CONFIGURATION PARAMETERS ............................................................................................................... 7 1.6 ANCILLARY EQUIPMENT .............................................................................................................................................. 7 2 SUMMARY OF TEST RESULT ............................................................................................................................. 8 3 TEST FACILITIES AND ACCREDITATIONS ............................................................................................................ 9 3.1 TEST LABORATORY ..................................................................................................................................................... 9 3.2 ENVIRONMENTAL CONDITIONS ..................................................................................................................................... 9 3.3 MEASUREMENT UNCERTAINTY ..................................................................................................................................... 9 3.4 TEST SOFTWARE ...................................................................................................................................................... 10 4 LIST OF TEST EQUIPMENT .............................................................................................................................. 11 5 TEST ITEM AND RESULTS ............................................................................................................................... 13 5.1 ANTENNA REQUIREMENT .......................................................................................................................................... 13 5.1.1 Standard Requirement ............................................................................................................................. 13 5.1.2 Test Result ................................................................................................................................................. 13 5.2 CONDUCTED EMISSION ............................................................................................................................................. 14 5.2.1 Limits ........................................................................................................................................................ 14 5.2.2 Test Procedures ......................................................................................................................................... 14 5.2.3 Test Setup.................................................................................................................................................. 15 5.2.4 Test Result ................................................................................................................................................. 15 5.3 RADIATED EMISSION ................................................................................................................................................ 18 5.3.1 Limits ........................................................................................................................................................ 18 5.3.2 Test Procedures ......................................................................................................................................... 18 5.3.3 Test Setup.................................................................................................................................................. 18 5.3.4 Test Result ................................................................................................................................................. 19 5.3.5 Band Edge - Radiated ............................................................................................................................... 23 5.3.6 Spurious emission in 1000MHz-25000MHz ...................................................…

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Photographs of the Test Setup Model: Questyle M18i Max Radiated Emission Below 1GHz Radiated Emission Above 1GHz Conducted emission