Welcome,
If you do a (Forum) search you should find something. I just did that and got this response:
Search found 9151 matches: +Speakers
Search found 1416 matches: +Amps
You would need to enter a search topic using the Search button just below the Forum header and the 3rd button from the left.
When you mention to a USB amp, assume you are referring to an external audio card such as a Motu UltraLite-mk3 Hybrid Interface? This box gives you 8 outputs.
https://www.ebay.com/itm/284230659614?epid=97029566&hash=item422d77ae1e:g:vGwAAOSwIe1gS-h5
Hope that helps.
Rgds,
Ed