When making a purchase and the ad states the seller had new caps installed the first thing you should ask is who did the work. If done by the seller himself you have to wonder if the new caps are the same value and if installed correctly. If non-polorized & they are the correct value, there should be no concern here. But your stating the original caps are the cause & obviously there is a problem. Audio Research is so darn expensive, I know because I inquired about repairing an ARC SPll MKll power supply. The price to repair this was shockingly high, still have it boxed up in my attic. Interestingly, Audio Research is now up for sale but from what I understand the buyer has to maintain their high standards & meet certain criteria. Tonedef 33, if you have a schematic take the SP6 to a reliable local tech. If you don't have a schematic call ARC to see if they could send one, it will speed up repairs. The posts/advice above & who to contact are excellent!