We don't give a shit about blaming people (at least I don't), but with amps like the KGSS the ownership history can actually help diagnose the problem. Even if you don't know who owned it before the guy who sold it to you, someone here might. That happened with my own little whore of a KGSS. I've said this all before, so I'll stop.
One last thing, I think your paranoia about disclosing the seller's info is misplaced and a bit weird. We are perfectly capable of determining for ourselves if someone acted honorably or dishonorably in a deal.