Basic DAC board

Hi im looking for an really basic dac board thats basically usb in and audio out.
The only requirment is external supply input becuse my computers usb power is really dirty and its really easy to hear the noises with any amplifier that i plug in through the built in audio out or an cheap dac board from an usb headset.
i also dont want anything stupidly expsnsive 50$ max preferably 30$
 
All computers have dirty ground planes, and those will link to your DAC through the USB shield whether it uses external power or not. The real problem here is that the cheap DACs in your headet and on your motherboard don't properly separate analog and digital grounds and filter the power properly.

I'd advise trying a cheap but properly designed phone dongle before attempting to cobble something together. Phones are just as dirty as PCs and generate a lot of RF that will quickly expose a poor design. The classic option is the dirt-cheap Apple USB-C adapter. It's got aceptable performance and chances are that this will solve your problem.
 
You can try a two-part setup: a usb-toslink converter and toslink-fed dac, the latter powered from external power source.
Or if your computer has a s/pdif or toslink port, try connecting a dac board through it, many if not most such boards have both toslink and s/pdif ports.