tl;dr The SR35 is a perfectly paired down device that is delightfully pocketable and transportable. There are some hiccups, it’s not perfect, but it could be perfect for you!

This is a narrative review instead of an analytical review. Come with me on my journey. My first DAP was the Questyle QP2R. I was unhappy with how lifeless it sounded with whichever earphones I had then. I then moved to the Astell & Kern SP1000M. I fell in love with the SP1000M. The UI was what I wanted. It sounded so lively and FUN! I enjoyed it so much that I invested in a set of 64 Audio Tia Fourté and a PlusSound X8 palladium cable. This chain rivaled my desktop setup in pure listening enjoyment. This is my foundation of good portable audio.

I then made the mistake of trading the SP1000M for a Fiio M17. I wanted specific features mentioned on the Fiio website (AirPlay, 1/4” port, app store). I also did not have enough data about how players compared to each other, and I assumed one flagship device would not sound noticeably different from another flagship device. Comparing the M17 to the SP1000M, I found the sound of the M17 to be very digital while the SP1000M sounded much smoother and more musical to me. It’s like I could hear the bits with the Fiio. It simply was not as enjoyable to me. I also found that none of the features that made me want it worked well. The M17 is a brick packed with so many features that suck and a UI that needs to be dumped down a toilet and flushed.

So here I am now with the Astell & Kern SP35.

How do I feel about it compared to the M17? As someone who takes public transportation, walks dogs, and is generally very active and mobile, I find that the SP35 is a dream come true in most ways. The size of the M17 made me carry it in a murse (Music purse, naturally). The size of the SP35 lets me toss it in the murse quickly and easily, but it’s also totally pocketable. The physical design of the SP35 feels SO GOOD in the hand. As consumer technology has stagnated and the only form factor that exists is the candy bar (Or brick, in the M17’s case), genuinely intelligent design and thoughtful placement, arrangement, and restraint is hard to find. The M17 was covered in buttons. It was impossible to quickly do what I wanted to do while it was in the murse. Even when I was holding it in my hand, I would sometimes need to double check which functions were on which side. The SR35 is perfectly tidy in that it has a power button, back, play/pause, and skip. The buttons are on the same side, and they are raised enough to run your thumb across them blindly to orientate yourself. The skip is at the bottom, so you can easily find it and move onto the next song. The volume wheel on the SP35 feels infinitely better than the M17’s. There is a bit more resistance to the wheel and guarding around it, contributing to the SR35’s pocketability. I also assess that it will last longer than the M17’s, although the M17 does have volume buttons as an alternative. Overall, the SR35 fits in the hand in a very organic and thoughtful way while the M17 simply does not fit in the hand.

The UI has posed some unique challenges for me. Straight up, objectively, inarguably, the SR35 has an infinitely better UI design than the M17. The Crimson UI is PERFECT for people who listen to whole albums front to back. You simply find the album and there is a software button that plays the whole album. It’s simple, straightfoward, and gets you to your music. I was never able to understand the M17’s AWFUL UI design. Depending on what screen you were on, “play” could play a whole album, or just the first song of an album, or the whole album randomly. There is no thought or consistency in the M17’s UI. ONE BIG CAVEAT HERE: If you are a Mac user, it is essentially impossible to sync music from a Mac to this device. I have tried every route I can find and there is always a roadblock. While I haven’t discussed audio quality yet, please consider that I am so much more happier with this device compared to the M17 that I am figuring out how to use a Raspberry Pi to sync music to the SR35.

Okay, it’s super portable and delightfully designed, but how does it sound? Reflecting on my preference for the musical sound of the SP1000M over the technical but lifeless M17, I found the SP35 to be an interesting compromise. I wasn’t sure what contributed to what I liked about the sound of the SP1000M. Was it a component thing like AKM chips? Was it some sort of hidden software that brought it to life? Listening to the SR35, I found that it noticeably lacked the detail present in the M17 and SP1000M. I feel like this is understandable. The Ciruss Logic CS43198 DAC chip is a budget-friendly chip. It just doesn’t have the horse power for the detail that higher end DAPs have. BUT! I will say that the smoothness and musicality that made me love the SP1000M is here. I don’t know how to quantify this. It may not sound as “good” as the M17, but it is much more enjoyable to listen to. It’s a similar compromise to my desktop amp selection. I have compared my beloved Schiit Mjolnir 2 with tube preamp to numerous summit-fi amps. Consistently I have picked the Mjolnir’s sacrifice of detail for it’s tubey bloom over technical powerhouses. I am glad to do the same with my portable audio as well, at least until I can justify spending the money for a Ultima device again.

One note I will mention: I am frequently getting audio hiccups when listening to local files on the SR35 in quad DAC mode. I have not had the time to troubleshoot this or dig into the possible causes. At the time of writing, I have been using this device for about 3 days. I will update this review once I have more to say about the audio stuttering. EDIT: I have found that switching from quad DAC mode to 2 DAC mode, then switching back to quad DAC seems to resolve this issue. I will report this to A&K.

EDIT: Bumped up my rating from 3.5 to 4 because of a software update to make the M17 a proper Roon endpoint. You can now listen to Roon with the full guts of the device. There is a NOTICEABLE sound improvement. Good riddance to the Fiio player. Overall, the device is still unjustifiably big unless you are going to be using it specifically for full-sized headphones and the sound quality isn’t quite on par with summit-fi players, but this software update means I can stop checking eBay for an SP3000 for a bit longer. AirPlay is still unusable.

Gear tested with the Fiio M17: 64 Audio Tia Fourte with balanced, palladium-plated Plussound X8 cable, Audeze LCD-5 with single-ended, silver-plated Plussound X8 cable, and Dan Clark Audio Ether 2 with single-ended DCA VIVO cable. What steered me toward the Fiio M17 was its ability to use Apple AirPlay. If that was also something that caught your attention, understand this: The lag between an Apple TV and the Fiio M17 over Apple AirPlay is unusable. It’s about a 3 second lag/delay, considerably worse than just using Bluetooth. So what’s left? A decent DAP that tries to do everything and continually stumbles.

Coming from an Astell & Kern SP1000M, I deeply appreciate access to the Google Play Store and Resilio Sync (By far the best file-syncing option). Roon works great, although I would say that the strength of the Wi-Fi reception of the M17 is “medium”. Roon also has to go through Android, so it is not lossless. The sound is good, not great. Despite the marketing department coming up with the term “Desktop class”, it is embarrassing to compare this to a good desktop setup. It has the power for full headphones, but it lacks good, dynamic sound. It feels flatter, less slam, and lethargic compared to the A&K SP1000M. I honestly considered the SP1000M and the Tia Fourtes to be one of the best sounding combos of any audio gear I have owned. When I plug the Tia Fourtes into the Fiio M17, I would say that the sound is better than the 2nd gen AirPods Pro, but barely.

It also has some bizarre quirks. The “Enhanced” headphone mode can ONLY be activated with the dumb charging brick. The brick is DC power! You have USB fast charging ports! You cannot activate the enhanced mode with USB power. WHAT IS WRONG WITH YOUR ENGINEERS? The Pure Audio mode UI is generally very good, but of course it has some obnoxious ticks to it. Searching for music is clunky. Manually updating your library seems wildly outdated. When browsing music, UI play buttons will either play music in series or play it randomized, and there is no indication what you’re going to get when you press the button.

I think this is a mediocre player that is offensively large. Like… you cannot comprehend its size until it is in your hands. Yes, it does have a full, real 1/4” port, which is insane. But even with earphones and the lowest gain setting and Wi-Fi turned off, the battery life is relatively decent. I haven’t thoroughly tested it, but I still have to charge it pretty often.

Overall, I think you have to have some extremely specific needs to justify the Fiio M17. I think that the vast majority of people can get similar sound for less, or spend a little bit more for better. Personally, I am definitely trying the Sony NW-WM1ZM2 and the A&K SP3000 when I get a chance.