McIntosh 501's, Mcintosh 7000

I would think the C200 would send a much more detailed and open signal to the 500's. At which point did you change the IC's between the two? And have you tried others? And is all new gear and maybe just needs to break in?

I think Theo's points of break in and cabling are valid.

It also may be that the 500's are bringing out more of the speakers nuances than the Ma7000 did. It might be controlling the lower frequencies better and therefore it sounds darker. If that's the case then repositioning the speakers may help (along with other tweaks) to get them to open up and be better balanced.

When you change more than one thing in a system you really have to do a lot of experimenting to sort through it all.

I use to own the Mac 602. Loved it but it didn't play well with ALL the speakers I put on it.

I had problems with my Monster HTS 5000 and McIntosh gear. It sounded horrible connected to the Monster. Try plugging your equipment directly into the outlet and see if that helps. I've since upgrade to a Richard Gray 1200 that works in parallel versus inline. This allows unrestricted amperage to your equipment. I personally plug my amps/subs directly to the outlet and connect the more sensitive gear like preamps and source units to the 1200. How big is the circuit that your plugging into? I'd recommend a separate 20 amp for the 501s and a separate 15 or 20 amp for the rest of the system. You may want to purchase a Kill a Watt meter to see how much current you are actually pulling. My JL F113 sub during the Omaha beach scene in Saving Private Ryan maxed out the meter at 20 amps! Good luck and don't give up yet.

Going from Nordost to Speltz cable seems like a switch destined to rob your system of some detail. The Speltz are great for the money, but they're not going to give you all the detail your amps are capable of. I got rid of mine in favor of LAT Int SS1000 and the difference was not subtle. Still running Nordost ICs too.