Emotiva USP-1 Preamplifier is in excellent working condition. These preamplifiers are no longer sold by Emotiva and it's a chance to own on the best budget preamp in less than $500 price range.
The best part of this preamp is it's Bass Management – Low Pass/High Pass Filters (see pics).
Check some of the reviews online.
Physically it is in very good condition except a mark at the top which might be removable but I haven't tried it. 8/10 - Very good - Perfect front face, 1 minor flaw on top or side is acceptable.
Reasonable offers are encouraged.