Astell & Kern A&norma SR25 MKII Portable Music Player

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SR25 MKII Portable Music Player, by Astell&Kern.

The SR25 MKII offers more versatile connectivity options with the addition of a 4.4 mm balanced output (for the first time in an A&norma player), LDAC, plus Qualcomm® aptX™ HD, which support and deliver true audiophile sound quality.

True to the core values of Astell&Kern, high fidelity sound lies at the heart of the SR25 MKII, delivering exceptional audio performance to a diverse range of music lovers. The most distinctive feature of the Astell&Kern A&norma product line is its seriously compact form factor. However, the SR25 MKII offers more detailed sound than its predecessor, allowing the clear expression of each and every instrument and vocal note.

This new pocket powerhouse may have a familiar look and feel but it delivers superior sound through Astell&Kern’s latest advanced audio design technology. Presenting more detail than its predecessor, the natural high-resolution sonics deliver clearly defined upper and lower ranges and a deeper, more rounded sound.

The addition of the balanced 4.4mm headphone jack, joining the 2.5mm (balanced) and 3.5mm (unbalanced) outputs, means music fans can connect an even wider variety of headphones, IEM’s and devices. The 4.4mm balanced output provides improved dynamic range and bass response, supports a wider soundstage, while capturing clear imaging and subtle details in the audio source.

As with the first-generation model, the SR25 MII handles an array of high-resolution music formats and sample rates. Support for native playback of DSD256 and 32-bit/384KHz PCM high-resolution audio, brings every music fan closer to hearing the artist’s original studio sound. Should you want to listen to your favourite hi-res music over a wireless connection, the SR25 MKII features the latest high-definition Bluetooth wireless codecs: LDAC and aptX™ HD.

The SR25 MKII also adds Replay Gain functionality to the mix. This automatically and uniformly adjusts volume playback from sound sources up to 24-bit/192 kHz so playlists can be enjoyed throughout without reaching for the volume.

First introduced in the A&futura SE180 player, AK File Drop ensure easier wireless file transfers. Users can wirelessly transfer files through a PC, smartphone, or FTP program located on the same network to make music management even more convenient. Secondly, the new BT Sink function connects the SR25 MKII to an external device, such as a smartphone, via Bluetooth, enabling music to be played back in high-quality on the Astell&Kern player.

Astell&Kern players apply shield cans to eliminate electromagnetic interference caused when internal components are in operation. First introduced in the higher-end A&ultima SP2000T, the SR25MKII has taken further measures by applying highly conductive, hyper-pure silver plating on the existing shield cans for extra defence against these sound performance-effecting disturbances.


  • SR25 MKII is a true mass premium product.
  • Improved audio quality compared to the SR25.
  • Versatile connectivity with addition of 4.4mm balanced output support.
  • Energy-efficient design resulting in 20 hours of continuous playback.
  • Supports two-way Bluetooth and high-definition codecs (Qualcomm® aptX™ HD, LDAC).
  • ReplayGain automatically maintains constant volume.


  • Model: SR25 MkII
  • Body Colour: Mercury Dark Silver
  • Body Material: Aluminium
  • Display: 3.6-inch (720 x 1280) TFT LCD
  • Supported Audio Formats: WAV, FLAC, WMA, MP3, OGG, APE, AAC, ALAC, AIFF, DFF, DSF, MQA
  • Sample Rates: PCM 8 - 384 kHz (8/16/24/32 bits-per-Sample) / DSD Native, DSD64 (1 bit 2.8 MHz), Stereo / DSD128 (1 bit 5.6 MHz), Stereo / DSD256 (1 bit 11.2 MHz), Stereo
  • Output Level: Unbalanced 2 Vrms │ Balanced 4 Vrms (Condition No Load)
  • CPU: Quad-core
  • DAC: Cirrus Logic CS43198 x2 (Dual-DAC)
  • Decoding: Support up to 32 bit / 384 kHz Bit to Bit playback
  • Input: USB Type-C input (for charging / PC / MAC)
  • Outputs: Unbalanced Out (3.5 mm), Balanced Out (2.5 mm only 4-pole supported / 4.4 mm only 5-pole supported)
  • Wi-Fi: 802.11 b/g/n (2.4 GHz)
  • Bluetooth: V4.2 (A2DP, AVRCP, Qualcomm® aptX™ HD, LDAC)
  • Dimensions: 63.5 mm [W] x 108.3 mm[H] x 16.1 mm [D]
  • Weight: About 178 g
  • Firmware Upgrade: OTA Supported
  • Operating Temperature: 0C - 40C (32F - 104F)
  • Frequency Response: ±0.014 dB (Condition 20 Hz ~ 20 kHz) Unbalanced / ±0.011 dB (Condition 20 Hz ~ 20 kHz) Balanced / ±0.010 dB (Condition 20 Hz ~ 70 kHz) Unbalanced / ±0.012 dB (Condition 20 Hz ~ 70 kHz) Balanced
  • S/N: 122 dB @ 1 kHz, Unbalanced / 124 dB @ 1 kHz, Balanced
  • Crosstalk: -138 dB @ 1 kHz, Unbalanced / -144 dB @ 1 kHz, Balanced
  • THD+N: 0.0006% @ 1 kHz, Unbalanced / 0.0005% @ 1 kHz, Balanced
  • IMD SMPTE: 0.0004% 800 Hz 10 kHz (4:1) Unbalanced / 0.0003% 800 Hz 10 kHz (4:1) Balanced
  • Output Impedance: Unbalanced Out 3.5 mm (1.2 ohm) / Balanced Out 2.5 mm (1.8 ohm), 4.4 mm (1.7 ohm)
  • Clock Jitter: 25 pS (Typ)
  • Reference Clock Jitter: 70p s
  • Built-In Memory: 64 GB [NAND]
  • External Memory: microSD x1 (Max. 1 TB)
  • Battery Capacity: 3,150 mAh 3.7 V Li-Polymer
  • Charge Time: About 2.5 hours (5 V 2 A General Charging)
  • Playback Time: About 20 hours (Standard FLAC, 16 bit, 44.1 kHz, Unbalanced, Vol 50, EQ Off, LCD Off)
  • Supported OS: Windows 7,8,10 (32 / 64 bit) MAC OS X 10.7

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