Douk Audio U10 Mini Vacuum Tube Headphone Amp Amplifier 3.5mm 6.35mm for PC - High Fidelity Stereo Preamp for Home Speakers & Hi-Res Audiophiles

Pros: Excellent sound quality, lots of volume/power, makes all music sound a little warmer and sweeter, brings out details, less listening fatigue, good stereo separation. Packaged well, arrived in great condition. Build quality is great.Cons: No included power supply, only a USB to DC cable (I do not recommend to use a PC USB port (dirty /noisy power and often not enough amps), you WILL need to purchase a separate power supply or need to make sure the USB power source you are using can actually output the required amps and volts cleanly otherwise you will get issues with distortion or it just won't turn on, my power back could not supply the appropriate voltage/amps over USB A but could over USB C.Other comments: the little light up plastic insert is silly, and completely unnecessary, I would rather there be no led light at all, I may open it up and remove those LEDs. Also I sort wish it had a little cage or bars to protect the tubes from accidental damage or impacts, but that isn't a por or con just a opinion.

"Using this pre-amp with the AKG K240’s and a power supply has been an amazing listening experience. The sound is incredibly clean and neutral, with no hums or unwanted noise. The build quality is excellent, and I love how compact it is—it doesn’t take up much room on my desk. The recommended power supply works perfectly, and the volume control is fantastic; I don’t need to turn it up very high to get an enjoyable listening experience."

Update: Second time turning it on, and it refuses to send an audio signal out, even after letting it warm up for 15 minutes. This was plugged into a USB port on a desktop surge protector.The U10 definitely produces a bit heat and as well as a bit of a smell. Sometimes that's normal for new electrics, however considering it appears to have died on me, that likely was the warning sign something went wrong with this device. Possible fire risk. Be warned.- - -I honestly did not know what to expect with this amp. First time using anything with tubes in it. I have an HE400se and an HD700 which could have benefitted from more juice. The HD700 in particular were supposed to lose a bit of their harshness with a tube amp. Unfortunately, with the Douk Audio u10, it is the opposite.The audio became a bit harsher and with less resolution. It actually sounds worse than just plugging it into my computer or the GSX1000 in stereo mode.Some are saying the quality of the audio is clean, but its definitely getting a bit dirty in the process and not in a good way.The headphones I tested it with were the HD700, HD598, HE400se, V-Moda Crossfade, KPH30i and EPOS H6pro.So while I find the audio quality WORSE after using this amp, it can clearly cover the more demanding headphones out there.Can't say I recommend this, but keep in mind that is due to my limited experience with this kind of Amp. As I am mostly on the computer, I use the GSX1000 as both the DAC and Amp. Including the Douk to the chain did not help much.

having worked as a professional sound design and music composer in video games for 20+ years, i was a bit skeptical that for the low price (about $45) this device wouldn't do much or sound decent at all. but honestly, afaikt so far just about everything i've sent through this sounds better! warmer, more rounded (especially the digital synths), slightly fuzzy around the edges (in a pleasent way). obviously if you send a crappy quality mp3 or internet streaming(usually low fi 128kbps) this won't improve garbage compressed audio much. but if you have .wav or .flac, this will surely add something special when listening to those lossless quality files. tbh, i feel i could run my stems or mixes through this during a mixing session and get a really nice tube drive sound. for certain personally projects i feel i could even run the masters through this to add a nice 'little something extra' analog, since i tend to work mainly 'in the box'.ive even been able to power this via the usb c(with a 4x usb a hub) from my laptop and then fed audio from the same laptop through this. there was only a subtle ringing tone when i turned the volume all the way up. but i just crank the output volume on the laptop and kept the volume knob on this tube amp down, and the ring is not noticeable at all. ymmv there, as i read some others got terrible noise when they tried this kind of setup.i love that it's usb powered and you could easily take it on the road. the tubes sticking out do seem quite fragile obviously, and get a bit hot (probably normal behavior) so im aiming to be extra careful if i need to pack it or move it after heavy use, by letting it cool down completely first.overall id say this thing is a great deal and pairs will with my koss pro4aa's. sounds quite warm and lovely and has a nice look and feel (the volume knob is smoooth). really glad i bought it!

Great little unit... Increase in music power and clairity in my headphones and audio speaker system. There is slite pop in my speakers (only when turning on)!

Cool and beautiful sound. My son uses this when recording guitar, when i have not stolen it. Good volume, tone, and looks.P.S. i am a bit of a sound snob, just not going to bore you with tech!

So far I've owned my unit since May of 2024 and haven't had any issues. I've been using my Audioengine D1 DAC as a preamp going into the U10 with great results. Really helped liven up my HD600s that the D1 couldn't really do by itself. So long as you use a good 5V source you won't have any issues with your U10. The soft amber glow from the LEDs through the tubes is a nice touch at night.