About the Astell&Kern A&norma SR25 MKII

A value-packed portable player for for high-res music lovers
A value-packed portable player for for high-res music lovers
The SR25 MKII includes Astell&Kern's latest audio design technology for the best performance yet from a player in the company's moderately priced A&norma Series. This player also comes with some nice conveniences, including two-way Bluetooth and automatic gain leveling for consistent volume across various music sources.
Made for high-performance sound
The SR25 MKII has a quad-core processor for lightning-fast and accurate decoding. Dual built-in high-performance DACs - one for each stereo channel — deliver bit-perfect playback of high-res files up to 32-bit/384kHz. The player also gives you native playback for 1-bit high-res DSD files up to 11.2MHz and support for high-res MQA audio.
You can connect the SR25 MKII to a set of high-performance headphones and enjoy exceptionally detailed sound. The player has a standard 3.5mm stereo minijack plus 2.5mm and 4.4mm balanced outputs for compatible headphones.
Two-way Bluetooth® convenience
For wireless listening, the SR25 MKII features built-in Bluetooth. Stream music from the player to your Bluetooth headphones or speakers. The SR25 MKII offers Sony's LDAC high-fidelity wireless music streaming to compatible products, for better sound via a Bluetooth connection.
Bluetooth receiver mode (BT Sink) lets you pair a compatible source like a smartphone and take advantage of Astell&Kern's superior audio circuitry and headphone amplification for better sound.
Expandable memory
The player comes with 64GB of internal memory. A microSD card slot lets you add memory cards up to 1TB, for ample storage. And of course, you can have more tunes on extra cards and bring them along.
Product highlights:
- Featured in our article: Best portable high-res music players for 2023
- compact high-resolution portable music player
- plays a wide range of digital music formats, including MP3, FLAC, WAV, ALAC, DSD, and MQA
- native playback of high-resolution audio files
- up to 32-bit/384kHz for PCM and 11.2MHz for DSD
- 64GB internal flash memory
- microSD slot for cards up to 1TB
- built-in rechargeable battery lasts up to 20 hours
Display and controls:
- 3.6" high-definition touchscreen display
- analog knob on the side controls volume and power
Processing and wireless features:
- dual Cirrus Logic CS43198 digital-to-analog converters (one each for left and right channels)
- built-in 2.4GHz Wi-Fi (802.11 b/g/n)
- Bluetooth 4.2 transmission for playing through wireless headphones and speakers
- Bluetooth receiver mode (BT Sink) lets you pair smartphones and other devices and use the SR25 MKII as a high-quality DAC
- supports aptX HD and LDAC formats for high-fidelity streaming
- ReplayGain automatically adjusts sources with different volumes to an identical level for smooth, seamless playback from your favorite playlists
- powered by a fast quad-core CPU
Connections and specs:
- high-speed USB Type-C port (cable included)
- 3.5mm unbalanced headphone output
- frequency response: 20-20,000 Hz
- 2.5mm balanced output (4-pole)
- 4.4mm balanced output (5-pole)
- output impedance:
- 1.2 ohms (3.5mm unbalanced)
- 1.8 ohms/1.7 ohms (2.5mm/4.4mm balanced)
- total harmonic distortion @1kHz:
- 0.0006% (3.5mm unbalanced)
- 0.0005% (2.5mm/4.4mm balanced)
- signal-to-noise ratio @1kHz:
- 122 dB (3.5mm unbalanced)
- 124 dB (2.5mm/4.4mm balanced)
- crosstalk @1kHz:
- -138dB (3.5mm unbalanced)
- -144dB (2.5mm/4.4mm balanced)
- aluminum casing
- analog volume wheel provides fine level adjustments
- 2-1/2"W x 4-1/4"H x 5/8"D
- weight: 6.27 oz.
- warranty: 1 year
- Our 60-day money-back guarantee
- MFR # 3PPS227C-CMGRN1
What's in the box:
Astell&Kern A&norma SR25 MKII owner's manual
- Portable digital music player (Mercury Dark Silver)
- 40" USB cable (Type A USB on one end and USB-C on other end)
- MicroSD card slot cover (installed)
- Protective film
- Quick Start Guide
- Warranty
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More details on the Astell&Kern A&norma SR25 MKII

Product Research
Features
Overview: The Astell&Kern SR25 MKII (PPS22) is a portable high-resolution music player that delivers high quality playback. It is the third model in the A&norma line of devices from Astell&Kern, and an update of the award-winning SR25 from 2020. The SR25 MKII retains many features from its predecessor, but adds new design features, such as a 4.4mm balanced output, LDAC, and Qualcomm aptX HD. It has a 64 GB internal memory for storing your high-resolution music files, plus a microSD slot for external memory. The SR25 MKII has a large 3.6" LCD touchscreen display, plus built-in Wi-Fi and Bluetooth.
Construction: The compact SR25 MKII is only 2-1/2"W x 4-1/4"H x 5/8"D, and weighs 6.3 ounces. It has a Mercury Dark Silver aluminum chassis, and features an angled LCD touch screen. The SR25 MKII comes with a protective film to help prevent scratches on the screen and external finish. Analog controls include a rotary volume knob on the right side, and Power, Play/pause, Previous/rewind, and Next/fast forward buttons along the left side.
Digital Storage: The SR25 MKII has a built-in 64 GB (NAND) internal memory. You can also insert a microSD card in the external memory card slot on the bottom of the device. The maximum capacity of the microSD card is 1 TB.
Dual DACs: Like its predecessor, the SR25 MKII is equipped with two Cirrus Logic CS43198 Master Hi-Fi level DACs. The SR25 MKII adds a Quad-Core CPU to make your digital files sound better by removing noise and reducing distortion, and provide a faster, more intuitive user interface. The device plays any resolution of digital files up to 32-bit/384kHz, bit-for-bit. In addition, the device supports native DSD256 playback. The SR25 MKII supports the following Audio Formats and Bit Rates:
- Audio Formats: WAV, FLAC, WMA, MP3, OGG, APE, AAC, ALAC, AIFF, DFF, DSF, MQA
- Sampling Rates:
- PCM: 8kHz - 384kHz (8/16/24/32 bits per sample)
- DSD Native: DSD64 (1-bit/2.8MHz), Stereo / DSD128 (1-bit/5.6MHz) Stereo / DSD256 (1-bit 11.2MHz), Stereo
USB DAC Mode: The USB DAC function lets you connect the SR25 MKII for use as a sound card for your computer for better sound quality, compared to the built-in sound card. Connect the unit via USB from your computer and listen to your stored digital music with headphones, powered speakers, or on your home stereo. The USB DAC is compatible with 32- and 64-bit versions of Windows 8 and 10, and Mac OS X 10.7 (Lion) or later. In USB DAC mode, the device supports PCM 8-394kHz (8/16/24/32-bit) and DSD (2.8/5.6/11.2 MHz). Volume is controlled via the SR25 MKII's volume wheel, but the Previous, Play, and Next buttons are non-functioning in USB DAC mode. You may need to install a dedicated driver (available on Astell&Kern's website) to use the SR25 MKII as a USB DAC.
AK File Drop: You can easily transfer music files wirelessly through a PC, smartphone, or an FTP program, as long as they are on the same network. AK File Drop must first be enabled in the menu, and the ID and password entered into the FTP program of the device to be connected.
Balanced/Unbalanced Outputs: The Astell&Kern SR25 MKII offers both balanced and unbalanced outputs on the top of the device. Balanced outputs have an additional "cold" signal to compliment the hot signal, which reduces external noise and increases output. The outputs include a 2.5mm balanced, 4.4mm balanced, and 3.5mm unbalanced port. You can also connect an external audio device to the SR25 MKII by connecting to both the earphones port (ground) and the balanced port (LR), using an optional balanced cable available from Astell&Kern. Output voltages: Balanced 4.0V, Unbalanced 2.0V (no load).
User Interface: The SR25 MKII features a high-quality user interface to make it easy to find and select your music files, change the volume, and adjust the sound:
- 3.6" LCD Touchscreen: The full-color 3.6" LCD touchscreen has a resolution of 720 x 1280 pixels. The screen displays the title and artist of the currently playing song, along with elapsed and remaining time, with the album art in the background. On the touchscreen, you can touch the Play/Pause, Previous/Rewind, or Next/Fast Forward icons to control playback. You can make adjustments to the EQ, set the repeat and random modes, and add the song to a playlist, all using the touchscreen interface.
- Rotary Volume Knob: The SR25 MKII has a side-mounted analog-style rotary volume knob. As you adjust the volume, you can feel and hear the detents in the rotary knob, and view the volume range numerically and graphically on the display (0 to 150). In the menu, you can change the output to "Line Out", which locks the volume level at maximum.
- Hardware Control Buttons: There are four physical buttons on the unit: a top-mounted power button, along with side-mounted Play/Pause, Previous/Rewind, and Next/Fast Forward buttons. The power button turns off the screen with a short press, and turns the power on/off with a longer press.
ReplayGain: The ReplayGain feature automatically adjusts sound sources with different volumes to identical levels. This eliminates constantly having to adjust volume when playback levels differ between tracks. ReplayGain can be applied in the Albums, Playlists, or Folders menu. ReplayGain is only supported on 24-bit/192kHz or lower formats.
Gapless Playback: Gapless Playback allows you to play one song after another without interruption. This is only supported when playing music files with identical bit rates, sample rates, and channels.
Equalizer: The SR25 MKII's built-in 20-band equalizer that lets you adjust each band ±5.0dB in 0.1dB increments. In the advanced settings, you can adjust the bandwidth (Q) from 2.0 (wide) to 4.0 (narrow). You can save up to 20 User EQ curves.
USB-C: The SR25 MKII has a USB Type-C port on the bottom of the unit for connecting the unit to your computer for computer data transfer and for charging the battery. A Type-C to Type-C is recommended when connecting to a Mac that supports USB Type-C.
Wi-Fi Capability: The SR25 MKII features built-in Wi-Fi (802.11 b/g/n--2.4GHz), allowing you to connect the device and your computer to the same network for streaming and downloading music. The device must also be connected to Wi-Fi to search the Gracenote database. With the MQS Streaming Server software installed on your PC or Mac, you can use the SR25 MKII to access music files stored on your computer's hard drive or a connected HDD. In addition, the Wi-Fi connection allows you to receive notifications of new available firmware updates (OTA Upgrades), allowing you to download them on the spot.
Bluetooth: The SR25 MKII also has built-in Bluetooth V5.0 with LDAC, AVRCP, A2DP and aptX HD profiles for connecting a Bluetooth device to listen to music wirelessly. The LDAC codec gives you more options for higher quality wireless audio. To pair the device, you must place the unit within 8" of the Bluetooth device. The connection and audio quality will degrade at longer distances, and may disconnect at distances of 6-1/2 feet or more.
AK Connect 2.0: The SR25 MKII can stream or download music files stored on a computer on the same network. Using the AK Connect 2.0 app (available for Apple devices running iOS 9.0 or later or Android devices running version 5.0 and up), you can connect to a NAS or PC and control it with a smartphone or tablet. The app is compatible with DLNA and UPnP.
Power Requirements: The SR25 MKII is equipped with a 3150 mAh 3.7V Lithium-Polymer battery. The battery charges via USB in about 2.5 hours via the included USB Type-C cable (5V/2A USB adapter). A fully charged battery can provide up to approximately 20 hours of continuous playback time (based on FLAC, 16-bit, 44.1kHz, unbalanced output, volume 50, EQ off, LCD off). The Auto Power Off feature helps save battery life by turning off the device if there's no user input for a defined period (10 minutes to 24 hours). A sleep timer (10 minutes to 5 hours) and screen timeout (10 seconds to 3 minutes) are also available.
Protective Film: The unit includes a protective film to keep the touchscreen and the rear glass panel scratch-free.
Specifications:
- Frequency Response:
- ±0.014dB (Condition: 20Hz-20kHz) Unbalanced / ±0.011dB (Condition: 20Hz-20kHz) Balanced
- ±0.10dB (Condition: 20Hz-70kHz) Unbalanced / ±0.12dB (Condition: 20Hz-70kHz) Balanced
- Signal-to-Noise Ratio: 122dB @ 1 kHz, Unbalanced / 124dB @ 1 kHz, Balanced
- Crosstalk: -138dB @ 1 kHz, Unbalanced / -144dB @ 1 kHz, Balanced
- THD+N: 0.0006% @ 1 kHz, Unbalanced / 0.0005% @ 1 kHz, Balanced
- Output Impedance: Unbalanced Out 3.5mm (1.2 ohm) / Balanced Out 2.5mm (1.8 ohm), 4.4mm (1.7 ohm)
- Clock Jitter: 25ps, Reference 70ps
The Astell&Kern A&norma SR25 MKII replaces these items
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Great purchase! Worth every penny. I'm using it with sennheiser ie-800 earphones and the sound is simply extraordinary. Had a few hiccups when it came to transferring files but Crutchfields awesome customer support came to my rescue and it was up and running perfectly in no time!
Craig from Lititz, PA