FiiOK9Pro Amplifier High Resolution Desktop DAC Headphone Amps THX-AAA 788+/Support 384 kHz/Native DSD256/MQA Decoding/LDAC/AptX Adaptive/AptX HD

The sound and features of the FiiO K9 Pro are excellent. Unfortunately, and this does not seem to be the case with all units, I experienced sound drop-outs both over optical cable and bluetooth inputs.

Heavily built. Very good sound quality. Many ways to connect to and from it. Very good power for any headphones. I can recofnize nu hum when it is on full volume without inciming signal. I can find no drawbacks.

I recently upgraded from my "old" fiio k5 pro to the k9 pro ess due to my sundaras going faulty and me biting the bullet on an upgrade (currently amazon hasn't updated the listing but it is the ess version) and by god it really made my new arya stealths come to life. Widened the soundstage just a tad, made everything so much clearer and resolving, the base sounds a lot more punchy and controlled, just an AMAZING bit of kit.Just like pretty much every audiophile reviewer youtube has said, the fiio k9 pro ess is a steal at the price and I'm thankful I got mine at £550.Buy it you WON'T be disappointed and remember, buy once not twice.

Truly excellent headphone amp that gets the most out of my Arya Stealth's and Focal Clears

I have enjoyed FiiO products for years. I own a BTR5 and a K5 Pro. Both are excellent products. I've been using a tube amp (Xduoo TA-30) as my daily driver. It is truly an awesome amp with sound and looks to match! I've been wanting to add a solid state amp to my collection. Fast forward to the K9 Pro. I have been reading up/researching this amp since it was announced last year. DMS, Joshua Valour and Zeos (well respected headphone reviewers) all have given the K9 Pro a big thumbs up. Especially for the price. In fact DMS compared it to a device that cost $17k. I've been using the K9 Pro now for several days and I ,too, can say that this is indeed a superb device. It not only looks and feels like a flagship device but it has the sound to match. Bass is punchy, deep and clean. Mids are lush with just the right amount of warmth. Treble is loaded with detail and sounds silky smooth. Compared to my tube amp I would say this THX amp is on the analytical side. You will hear all kinds of micro details in your favorite tracks. My headphone collection includes HD800s, HD660S, HD6XX, HD598CS, HD560S, DT1990 Pro, Shure SE846 and several KOSS models. The single ended 1/4" jack drives them all with ease on the medium gain setting. I tried the 4.4mm balanced jack to see if there was any sonic difference. Other than it having even more volume they sounded identical to my ears. In fact I dropped the gain setting to low because there was waay more volume than anyone's ear should ever be subjected to. I do believe if you have hard to drive headphones this amp via the balanced jack will provide all the power your likely to need. The K9 Pro is an excellent addition to my collection and I can't wait to put some more miles on it. It sounds fantastic! FiiO definitely hit a home run with the K9 Pro.