I think the potential liability for modded amps (Berry EP/iNuke, Peavey IPR, etc.) would exceed the financial benefit. It's one thing for an owner to do something to a personal unit that one reasonably knows could impair its function. It's quite another to sell such a part.
As for something like a Crown K2 clone, I don't know whether that's feasible, given IP issues. But even if it is feasible, I suspect the market for people who want them would be quite small. Especially since it wouldn't have Crown's warranty or resale value. And such an amp, I'd assume, would not be properly safety-certified by an OSHA-approved NRTL. I cannot fathom why people would allow uncertified electronics into their home. (Note that a Dayton SA1000 has a UL stamp on the back. Likewise, a Crown XLS2500 carries a CSA stamp on the back. Others have stamps from ETL or other OSHA-approved testing labs.)
IMO, people who want quieter amps should either use amps known to have less active fans (e.g. Crown XLS Drivecore rather than Berry iNuke or Peavey IPR), or amps designed without them (e.g. Dayton SA1000). Or modify one's own part at one's own risk.
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