Douk AudioU10 Mini Vacuum Tube Headphone Amp Amplifier 3.5mm 6.35mm for PC - High Fidelity Stereo Preamp for Home Speakers & Hi-Res Audiophiles

This makes my 50 headphones sound like the 250 headphones in the store.I'm comparing the U10, with the U3, which is essentially the digital alternative to using tube amplification.Side by side there's some things that you should know:Only the U3 included a power adapter and if you are a musician, it is not the typical 2.1 x 5.5mm, it's the next size up. 2.3 or 2.5...it doesn't say.There's no bass or treble for tone adjustment on either model.The tubes take less than a minute to engage and it's on. The volume knob is a power switch by turning it all the way down.Now the good stuff;The U10 is the best sound. It compresses more than the U3, which is actually why it's preferable as a listening device. If you want more accurate sound the U3 is more accurate because it doesn't have this "warming" compression effect as volume increases.At this price point, I'm going to keep the U10 for just listening to music on my headphones. It's way more awesome.I mainly needed the headphone amp to practice guitar, so this was a great find.I hope it lasts.Thanks for reading, I hope it helps in your journey for improving your sound quality.

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.

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.

"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."

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)!