Hidden Gems in Pre-Owned Solid State Power Amplifiers?

Browse the listings for power amplifiers (e.g. under $5K) and you notice a myriad of Classe, Parasound, Bryston, older McIntosh and Mark Levinson and lots of Pass Labs.
So many in fact that you wonder why.
What are the true audiophile gems in the pre-owned solid state market? Thanks in advance.