SMSL DO400 Full Balanced Headphone Amplifier DAC Amp ES9039MSPRO XMOS-XU316 USB MQA DAC USB/AES/Optical/Coaxial/IIS Input 4.4mm/6.35mm/4-XLR Jack Output Headphone Amps (Black)

I just got the new firmware flashed and the performance is right there with much more expensive stacks I've got. To update, load the flash program and open the file included. Then turn off and hold the jog wheel 5 seconds while you hit the power switch to on in the back. It'll be a dark display with no LED if you did it. Then hit "connect" in the software and it'll take 15 or so seconds. If it finishes in 1-2 seconds it might mean your chose an incorrect flash file. Don't worry though, you can't brick these even if you do it, it'll run a check and skip over it.3 watts into 32 ohm really is good power, even for my Hifiman He6se (though doing a big preamp reduction for EQ will need more power). With stock settings, it'll power anything you have. They fixed a lot of issues in the cheaper models like the DL200, no sound tick when changing bit rates, it's all smooth. Also this doesn't run hot or even warm like some other powerful amps or combos.The sound is completely transparent, but there's filter and color options which in combination, really will customize the sound. The colors add distortion in the 2nd and 3rd harmonic, and the filters make a small difference. The default usually has the best performance, but it's a personal choice depending the music you like. It's a huge value compared to the Topping DX9 which has more power, but the price is sky high (and they sound the same). It's a combo unit so it always has perfect channel matching, which gamers will like since that improves imaging accuracy (provided your headphones are good also). The form factor hits full size amplifiers on it.The latest firmware is important since I updated right off the bat and didn't experience any problems with playback or other issues some other reviewers complained about. I have four of them currently, so I would have run into something, but it's smooth sailing on all of them. The balanced side has a higher gain setting, but the single end 1/4" jack is great for IEMs or even the Sennheiser HD700 300 ohm sounded great on that plug. I wouldn't go buy balanced cables until you try it first, they sound the same on either connector. Even the DT990 600ohm had plenty of power on the SE side.It's the value for money winner over similar offerings, and I can always add ampzilla in the future to expand since it's a 5.2volt DAC.

Lots of clean power if you need it. I’m not totally sure that I could tell the difference between the c200 and the DO400 dac section. But with power hungry headphones there’s a difference. I have the Dan Clarke audio open X, and they sound a bit anemic on the c200, but only when I compare them on the DO400. It’s probably placebo, but I also feel there’s a bit more musicality, less harsh trebles with banjos and violins, and the acoustic bass sounds more realistic. I prefer the heavier and larger footprint on this vs the c200. Using this with parametric EQ over Roon is endgame for me. Don’t feel like I’m missing anything sonically at all.

I was looking for an all-in-one solution to replace my Schiit Modi+ (DAC) and Topping A30Pro (amp) stack. My main purpose was to clean up my desk area, but I also wanted bluetooth and balanced connections, which neither the Schiit nor Topping had. My target price range was ~$500.After a lot of research, I landed on the FIIO K9 (ESS version). The FIIO has all the features I wanted, the build quality is excellent, and the sound and power were a step up from the Schiit and Topping stack. While I was satisfied with the FIIO, the SMSL DO400 showed up under "Inspired by your browsing history" and it had all the features of the FIIO but with more power and a remote. I decided to buy it and do a comparison.The DO400 sounded similar to the FIIO, though seemed to lack the same level of detail and neutrality, but it had more power. One thing I noticed was when I cranked it up near the top end of the volume on high gain, it seemed to only get loud and the music lost its fullness. The headphones I tested with were the Sennheiser HD6XX & 560S, as well as the Beyerdynamic 177X Go, and Hifiman Sundara Closed Back (which I returned due to an issue with the cable). While none of those are too difficult to drive (the HD6XX has the highest impedance and can handle quite a bit of power), the DO400 behaved the same on all of them. While I would never listen to anything at the level I was testing at for an extended period, it highlighted what I perceived to be a lesser-quality amp.Something else worth noting, which was the main factor of why I returned the DO400, was that I could hear distortion/static when changing the volume. Another reason I decided not to keep it was the subpar build quality. They used thin sheet metal for the case, the headphone jacks were "crunchy" compared to the ones on the FIIO, and the volume know felt cheap.To anyone considering this all-in-one DAC/amp, I would suggest that you take a look at the FIIO K9. It has the same feature set (minus the remote and filters), is better built, and delivers what I perceive to be higher-quality audio.