Antes de leer el resto de la reseña, NO HAY JUSTIFICACION para que un producto que vale 850 dolares falle despues de dos años, y he visto reseñas de menos tiempo. No compren este producto ya que la garantia es demasiado corta.------------Este producto me funciono por dos años, con uno que otro problema con los amplificadores de ves en cuando, pero nada que reiniciarlo no solucionara.Hoy la salida balanceada de los audifonos y la no balanceada dejaron de funcionar reproduciendo una señal incompleta.Decidi desensamblar el amplificador para ver si un capacitor habia reventado no es primera ves que he tenido que reemplazar uno en un producto de "HiFi" pero fuera de unos capacitores cerca de la fuente de poder que tienen algun tipo de pegamento termico (que dificulta removerlos) que se ven ligeramente, no pude ver daño evidente y sin un esquematico diagnosticar este producto es una aventura de dias, incluso para alguien con conocimientos en electronica. Igualmente desensamblar el producto require de desoldar el conector XLR del frente por una decision mala de diseño.El producto tiene una garantia muy limitada para el ratio de fallo que tiene, Fiio ofrece un mes de reemplazos garatnizados y un año de MANTENIMIENTO gratuito.Durante el funcionamiento normal del dispositivo la calidad de audio fue buena, pero siempre tuve dificultad conectandolo a otros amplificadores y usandolo puramente como DAC y esto por que el PCB no esta bien aterrizado, ya que lo abri la conexion de tierra pasa primero por el chasis y luego hacia el PCB, lo ilustre en una de las imagenes.El diseño termico es pesimo, esta muy restringido y no considero que sea un sistema que tenga que llegar a equilibrio termico o alguna temperatura para operar de manera correcta. El plastico que utilizo Fiio para cubrir el producto practicamente vuelve esto un sistema hermetico y por ende reduce el tiempo de vida del producto, esto seca artificialemente los capacitores mucho antes de tiempo, y hace que componentes digitales no se comporten bien por eso debe tener tantos bugs que no pueden arreglar con firmware.

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.

Had great expectations for this device as I wanted to upgrade from the FiiO K5 Pro to the K9Pro with BT. Is solid and well constructed, larger than the K5. Tested it in two different settings, as DAC from a PC connected to a Marantz AVR and Dolby/surround speakers, and from another PC to a pair of Audio Engine A5+ powered speakers. In the both cases the sound was not as crisp and brilliant as without it. I tested different settings with the AVR and only marginal audio quality improvement could be achieved. As with the powered speakers, the results were quite disappointing. I have all my music files on FLAC format and use Sony Music Center as the player. With the K5 the sound is great with nice separation and tonality, the sound is vivid. But when replace it with the K9 using the same settings and AudioQuest cables, the sound was dry lacking detail. Same results when using Amazon Music HD. Tested the BT option and sound quality was little better, but still dull.Not sure if I got a defective unit, or a used one as the box did not have the typical wrapping of a new product which was not nice. But for an almost $900 product with supposedly two DAC (one per channel) the sound quality was inferior. The music sounds much better with my $150 K5, so basically by paying $700 more you get a reduction in sound quality and that is unacceptable of course.Returned the K9 and ended up ordering the much cheaper K7 with BT because I need the wireless option and hope this only will produce better results. Will report on that one when it arrives.

This is not a review I thought I would ever write. Ever. See, I should not have this unit. Period. So how am I writing this? Do I own it? See the pics. So, how?It has been one of those years where I have been so busy that all the b-day, and other gift cards I acquired I never spent. I forgot all about them. About a week ago, I found an email with one and remembered I had more. I added them up and...damn! Really? SHOP!I tell you that little story because I don't operate in this price range. 500.00 and under is where I live. Every time I see a review about something costing 800-2k I want it but I will not spend that kind of money for something I would use daily but really for meetings and Spotify/Tidal. At night (for gaming) I use an SMSL unit on my desktop that is quite good.Most of the DAC/AMPS I have (and I have 6 full sets) and 1 'all in one' Topping DAC/AMP all under 500.00 bucks (minus one that was slightly more but just barely). All of them have very good sound and do what they are supposed to. My IEMs/Headphones sound fine with all of them with no issues.Enter the FiiO K9Pro - Bottom Line - The FiiO K9Pro is my end-game. I need nothing else. I am so blown away by the sound and particularly the sound separation I need nothing more. Every instrument, vocal, etc. has a place in the sound. Nothing is stacked on top of each other unless it was mixed that way. I spent about 1/2 a day plugging in IEMs (over 30) and Headphones (about 7) to the unit and even my 50.00-60.00 dollar IEM's sounded like I have never heard them before. I find myself closing my eyes and hearing just the slightest nuances in songs I have listened to 200 times. If you are looking at this unit, you have heard that before and, so have I. I am drop-dead serious when I say I am hearing things so subtle in songs I have been listening to for 30 years.Stats:- Bass - smooth as silk. Just a full, balanced, punchy (but not forceful) bass. I am a bit of a bass-head and I love it.- Mids - Love them. Forward but not screaming in my ear. They are where they are supposed to be tucked right into the song. Nothing sounds forced here. Just a singer singing.- Treble - This is where it can get interesting. Treble heads will not like this unit. The treble is tame and slightly pulled back. Love that about this unit. Nothing fatiguing about this unit with the treble at all. I have been listing to all kinds of songs today and not once have I said 'ouch!' This unit just handles it and handles it so well. VERY easy to just listen to for hours.Accessories: Plentiful. They even include a sticker (in color) you can put on the unit to help see the buttons better. Who does that?Composers - Led Zepplin, The Cars, Michael Jackson, Five Finger Death Punch, Cory Marks, Missing Persons, Judas Priest, Van Halen, and on and on.Streaming Platforms - Tidal, Spotify, and Qubuz.Headphones - Planar vs. Dynamic. - Planar headphones on the XLR or 4.4 sound the best. However, the 6.35 does a very good job which is what I have been using most of the time.Issue: When using an XLR to 3.5 adapters, the unit would stop producing sounds at about 12:00 on the volume knob. I am not sure why but I have to believe it has to do with the power being outputed. Just a guess. That said, extenders intended for the correct plug work well. For example, a 4.4 (male) to 4.4 (female) extension cable seems to work fine. It only happens when converting from one format to another.The End: I realize some folks will think the asking price is not that big a deal. I do. I have a family and for me, this is just a bit out of my range. If not for the gift cards, I would not have this unit. I am beyond lucky to be able to get this unit and be able to listen to a unit like this. For me, it's as close to perfect as I will ever get. I have zero reasons to look at anything else. I want to stop 'chasing sound' and just listen to my music library. This does just that. Simply an amazing DAC/AMP.

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

Man, have I had an interesting journey with headphone dac/amps. I started off with typical sound cards in computers. Going back to the 90's. Sound Blaster being the go to brand because they were simply the best back when. In the late 2000's early 2010s I moved on to an off brand called HT OMEGA which had this dope sound card called the Claro Halo and my god was a difference. At the time it was one of the best cards youc could get. Sadly its old school PCI and modern motherboard have nicked PCI from the board. Now its all PCI-Express.... And then in the most recent years I was using the Sound Blaster ZXR which was a mint little kit considering what was available for PC at that time. Then later I upgraded to the Sound Blaster AE-9 and was EXTREMELY disappointed. There were so many issues I don't even feel like going into it here.But eventually I started getting to dac/amp combos. I first went for just a headphone amplifier. At the time I was using a Schiit Magni 3 connected to my AE-9 via the RCA. But the audio was off, because of how the card was handling it. Instead of "side left/side right" like headphones would be, it was forward facing, so it was front left/front right which meant in games, I literally could not hear behind me. Such a poor design from SB. I wouldn't really "notice" that issue until the next upgrade. From there moved to a Schiit Magni 3 Heresy for the higher fidelity over the original. And yeah, it sounded better. Not a huge improvement, but enough that I could tell. Both products had volume pot failures. Meaning they got super scratchy. Hated it.After that I went for the Topping DX7 PRO. Man what a brilliant little dac/amp. Sadly my right ear went out after about a year of use. And Topping refuses to warranty it because I changed out the OP-AMPS. Why have OP-AMPS that you can change if that ends the warranty. It's literally like plugging in a headphone.... I know damn well they can't deny warranty, but I don't feel like lawyering up for a CHINESE company. They offered to sell me a new "motherboard" for $350 and it's like, if I am gonna spend money, might as well move on. Long story short, I won't buy Topping ever again.... and I will continue to tell others not to as well. Their loss. Never screw over your customers....Then I bought this mad house. The FiiO K9 Pro ESS edition. AND MAN. What a difference in sound. It is literally above and beyond anything I have ever heard. I am running this huge heavyweight (it's literally heavy and quite large compared to my Topping DX7PRO) with my Sony MDR-Z1M2 headphones via 4.4 pentaconn (aka balanced). Man I love the sound signature. Right away you can tell the difference. The bass is cleaner and deeper, the treble is nicer, and the mid range like vocals, pure extacy. Anyway, I haven't had any complaints using this new monster. Well worth the money. I honestly think they should make a cheaper "gamer" edition where it's basically JUST USB input, and then 6.35 or 4.4 output. XLR is a waste of time and money. YEAH I get there are tons of headphones on the market that support it, but you can easily get an XLR to 4.4. The 4.4 pentaconn connection is just the superior connection. No need for bluetooth or other outputs. By having less but still having the same quality, they could bring the price down. Maybe call it the K8. If they can figure out how to bring this quality down a few hundred dollars, they could take over the gaming market easily. At least that is my opinion.Anyway I have tested so many different musical genres'. From house/dubpstep/trance to country to metal to rock to classic rock to jazz to classical to oldies. I mean I have gone through it all. And I can't find any faults. In fact I find I am appreciating music more thanks to the K9. In fact, even when playing video games im hearing little details I never heard before. It's just that accurate. I cannot complain. I can't wait to listen to more music. I am just enjoying music that much more thanks to the quality.

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.