McIntosh MC-501s; balanced and unbalanced preamps;

I started an earlier thread on preamps for the Mcintosh MC-402, and then something funny happened on the way to the listening room: I wound up with a set of MC-501s.

So, first of all, I'm just wondering what other MC-501 users have for premaps?

Also, I've read somewhere that the new Mc amps can actually sound or perform better using unbalanced preamp outputs rather than balanced. Looking over the Stereophile review, I suppose one reason for this is gain. Thoughts, comments?
I am using a Theta Casablanca III w/ extreme dacs, balanced interconnects to Macs, lovin' it
I started with 402's and moved up to 501's and was pleased with the improvement. Preamp was Mcintosh C2200 with Mullard NOS tubes from Upscale. Very musical, lots of detail, and very non-fatiguing. And incredibly user-friendly. I made the mistake of discovering vinyl and as I moved more and more in that direction I found the 2200 lacking as a phono preamp. Last week my Aesthetix Janus arrived and blew my socks off: the change was not subtle. My system has a "liquidity" and presence that it has never had. And the phono pre is superb--much better than C2200 and Graham Slee I had tried. Only downside is that I can't power up my monoblocks and Janus with one switch. That was convenient, especially for my kids. But the Janus does have an excellent remote and all in all I am quite pleased with the change. I have used only XLR's with the 501's so can't comment on RCA sound. Hope this helps.
I'm using CJ Premier 14 with MIT SG EVO's - unbalanced, CJ doesn't offer balanced - awesome!
As a side note to Joe, TAS reviewers thought the phono stage in the C2200 was not nearly as good as the one in the C46.
The direction I would head would be toward a C200. Your 501's are completely balanced and so is the 200, so with xlr's you would have a balanced signal from at least the input of the 200 to the output of the 501. Good luck.
I've gotten interested in the C-100, which is basically the same as the C-200 minus something to do with home theater (this according to Chuck Hinton) and can be had for around three grand. I've also thought about something along the lines of an ARC LS25.

I've never seen an Aesthetix piece, but I've been interested...