I can vouch for this. I used it for years without issues(other than the shitty pot and legs falling off). One thing to note, it fucking oscillates with the stock and most opamp for no reason. Buy the OPA1656 and it will fix the oscillation and temperature issue. The power output is nowhere near that, on a german forum some1 tested it and it was around 600mW into 32 ohms. About powersupplies, any 5V phone brick will provide more than enough power and little noise. To people that said a linear supply “increased the sound”, its bullshit, the U3 have a boost converter inside which is way more noisier than the linear psu. I still use it when i travel since you cannot beat its small size and price,
You can get way better deals for way cheaper. It looks pretty ngl.