Review on Nobsound Mini Bluetooth 5.0 Power Amplifier - Stereo Hi-Fi Digital Amp 2.0 Channel 50W×2 with AUX/USB/Bluetooth Input - Wireless Audio Receiver - PC Sound Card incl. Power Supply (Silver) by David Reyes

Reviews that say it's "amazing for the size and price" are more likely to be true. Apocrypha. As for the USB DAC, I'd definitely say it's pretty decent and does its job well overall. I have this amp set to 1/4 on the volume control and it is good enough for basic room listening, with little noticeable distortion and no obvious clipping. Rear panel connectors work with both spliced cables and banana plugs; I reused some existing decent audio cables and it's funny how they pull down a small, lightweight amp. I have a few cons: - By default the device seems to switch to Bluetooth mode (blue status indicator) and I have to disconnect/reconnect the USB cable to switch back to USB (green status indicator). - Mode changes are accompanied by a completely unnecessary "USB mode” or "Bluetooth mode” announcement over the speakers. I wish this could be turned off as there is absolutely no need to hear when I turn on my system. When the USB is plugged in and the laptop source is silent, a pure hiss of white noise comes out of the speakers. It's _very_ noticeable. There is no such thing in BT mode. So let it sink in a bit: In USB operation there is pure *analogue* white noise when no USB signal is present. This leads me to believe that they don't turn off the amp even when the USB isn't transferring data. This white noise is also present in the "quiet" sections of the music. - I tried using it in BT mode and there is an obviously noticeable lag, at least 250ms or more. This is important enough as I can't watch a movie with it in BT mode. The power supply is quite light and never seems to overheat. Probably a typical buck converter design. It would be nice to place them behind an extension cord and turn off the power completely when you're done. Conclusion: The sound is acceptable as it is only a fraction of a normal USB DAC. However, the BT/USB switch and mode prompts turn off.