Cut the end off your XLR cable and put a RCA on it.  Changing the amp to a balanced topology is complex with no added benefit.

On the RANE site, are some technical papers.  I remember one of them details just about every cable configuration for going balanced to unbalanced etc and how to wire them.

I'ts good information.

... found it:

http://www.rane.com/note110.html

Jason

i can yak about it, as I've made up several balanced to unbalanced line cables (using those uh, pretty car stereo cables), using RCA to TRS, or XLR, but I'll show you where I learned it from:

http://www.mackie.com/pdf/1202vlzpro_om.pdf

Scroll down to "Appendix A: Connections, and the Mackie Boys tell you how to do it.

I will also throw this out: When using my sand amps, I never noticed any difference in wiring balanced line equipment to non balanced (and I went through pains to keep my audio cables away from power cables- there should be a freakin standard by audio manufacturers as to which side of the unit they run the power cable out of.. okay, I've calmed down) . But with my Zen 84CS amp, I NOTICED A DIFFERENCE. There is a loss in imaging and the "live" feel dissapeared.  My Beringer DEQ 2498 digital EQ, with absolutely no eq dialed in, did this. Same even when it was switched out of the circuit. I had to EQ it to try to bring it back, and that does not work!

When  I choose to use it this way, the only thing I found that works without ripping out the image and presence, was to throw another link in the chain (actually 2)-  an EB TECH line level shifter.

I have to go from an unbalanced line ( a Swissonic Studio D) through the EQ (balanced) and going back, unbalanced, to the Zen amp. What a freakin disaster. I don't worry about the effects patched through the mixer (not important on playback), but my signal chain going to the Zen could be better. If I'm doing some critical listening of a playback, I just rip everything out of the chain and plug into the Zen. It's that good.

Beside the dfference in levels associated with pro and "consumer level" ("Plus 4 vs -10dbv), there's an impedance matching problem when you try to make up cables to match balanced line to unbalanced, and vice versa.

As for the EbTECH Line Level shifters:  Plus side is that they are passive units (no power= no wall warts) Downside is that it is another link in the chain (in your case, for matching balanced to unbalanced. You can get them here:
http://www.musiciansfriend.com/srs7/g=home/search/detail/base_pid/189100/

I would think in your case (and hopefully mine, soon enough) that I can run everything balanced line (or digital) and then just make the final shift to unbalanced with the 84CS. I would still recommend looking into one of the Ebtech units.

When you get your amps, try using them with just a CD player hooked up on them (an unbalanced one with RCA jacks), and then listen to it with all your stuff hooked into it, with whatever you decide to use for matching the system up. I'tll give you a good idea as to how your system SHOULD sound.

Doc Sleep can probably elaborate more, as he does the same thing with his Zens as I do with mine (studio kinda stuff)

Thankyou everyone for your input,I now know more and have some direction.Lots of info to go thru,great links.I just tought it would all be simpler.The isolation transformer sounds like a good idea.Would be great to just make it a plug it in and forget.
                           Greg