Hi, so even if you got a quiet fan in to the PSU it would then be making excessive electrial noise?
That's bad luck
and as now mod'd won't be any warranty either. I would put it back together with original (or Scythe) fan and then use it somewhere noise doesn't matter or sell it on eBay or the like and buy a new one.
PSU whine is a bit luck of the draw and will also be strongly influenced by the system it's powering. I had a NeoHE that was lovely, till I put a GTX260 on it, then whined horribly. I had S12-II 330w power the GTX260 in a system fine, but swapping the GTX260 for a GTX285 made it whine badly.
For what it's worth the Antec Signature I have now seems to be free of whine whatever it's powering, so far....
I've not seen any reports of Enermax PSUs whining, the Modu/Pro82+ and Modu/Pro87+ have been revied by SPCR. The 82+ were very nice for their time but reports of fans going bad quickly. The 87+ looks excellent, 300rpm fan speed to quite heavy loads and 80+ gold efficiency, depends on your budget. The passive Seasonic X400/460 also excellent by all accounts and not over-priced, also worth a look at the higher X models, passive till need the fan to keep cool, then quiet.
Good luck, Seb