Douk Audio ST-01 PRO 200W Bluetooth Amplifier, 2 Channel Vacuum Tube Power Amp with USB DAC/Coaxial Optical Inputs/VU Meter/Treble Bass Control for Home Theater/Stereo Speakers (Upgrade Version)

I purchased this amp along with some Fluance speakers so I could have a very carefully controlled test bed for other components, speakers, etc. So far, pleasantly surprised at how punchy and strong this little amp is. I can quickly hook things up to this amp and run tests. I measured all the outputs with my diagnostic equipment and it tested out to the specifications listed for this amp. A very simple, powerful, punchy amp at a good price. Nice.

I've purchased three of these now, one for myself and then two as gifts. They look great with the glow from the tubes and the meter, giving a warm ambiance. The small footprint is easy to accommodate. The remote is easy to use. Bluetooth works well with good range. Hook up was easy and straight forward. I'm using Bluetooth, RCA, and optical. The sound is quite nice, with good power and detail.I listen to this everyday and I'm very happy with it.

Edit: Changing from 2 to 5 stars. It was the ac adapter that died, not the unit.I bought this to redo my PC sound setup for music production and also incorporate my tv into the mix with the optical in.Everything went as planned. It sounds great, but I'm coming from a smsl setup so it didn't blow me away or anything. But for the price and additional inputs and the cool aesthetics I was super happy. The remote being a huge huge plus.After a few weeks I watch some YouTube videos after waking up. Everything is great. Go to Hogwarts for a bit. Great.I leave for the day and when I come home it just won't turn on. Nada. Completely dead.I don't smell any magic smoke. Luckily I'm within my return time with Amazon so I don't have to deal with the manufacturer. I'll update this review when my new unit arrives tomorrow.The only thing that I don't like about this amp is what everyone else complains about. It'll go into standby if there is no sound for several seconds. I can deal with that. I don't see what everyone else is talking about with db scale not doing anything. It doesn't on low volume but it does when you turn it up. That's understandable to me.More importantly to me is that the volume goes up and down in notches. So the very lowest volume is still louder than I would like watching stuff at night when I fall asleep. That may just be the way optical comes out of my tv, I'm not sure yet.For the price, aesthetics and integrated DAC, I'm not sure it can be beat.

Sounds pretty good out of the box and can be upgraded with better tubes, external DAC, etc. I have a dozen other amps including the Fosi ZA3, vintage Kenwood and Marrantz, AVRs from Cambridge, Denon, Yamaha, NAD.The built-in DAC isn't great so I use an external DAC that I prefer, it's just the old $20 FIIO Taishan. I go optical out from my TV into the FIIO DAC and then RCA analog into the Douk preamp/amp, which is powering a pair of vintage ADS bookshelf speakers. Recently tried it with my SMSL SU-1 DAC and that was even better.Needed a small form factor to fit the space. Been using it for 18 months, with no issues. The tubes definitely change the sound. It's fun to experiment with different tubes and they're readily available on eBay, often for $20-30 or so for a matched pair.Everyone on Amazon gets the Riverstone Audio JAN 5654W tubes that are marketed as an "upgrade" but I didn't really care for them. Sounded dull and rolled off to my ears. I prefer old soviet-era Voshkod "rocket" tubes. They have a more dynamic hifi sound with extended highs and lows.The VU meter doesn't work very well for me (maybe by speakers are too small/efficient to move the needle at regular listening volume?) but that's kind of a gimmick anyway. Overall worth it for the tube preamp and TI class-D amplifier functions that I use it for.This can be a good option if you like tubes or want to try them out. Also good if you need the digital inputs and Bluetooth built-in, as those are usable if not the greatest.

What a great little amp. I have a Sansui transistorized amp from the late 70s in my shop, (65? watts) and ran it against this little champ. Very good audio quality! And the feature set vastly outweighed my good old friend. I sucessfully drove 2 Bose Direct/Refecting 'bookshelf' speakers hard enough to be heard far outside my closed doors- Bass response, well two little pentodes don't quite get there, but danged good overall, and for a LOT less money. Fun and cool gizmo!

Works well, intuitive design, and the tubes are surprisingly small. I hooked it up to some floor standing home theater speakers and it had no problem driving clean sound directly from my phone through the integrated Bluetooth.