how many folks have +10kVA trannys before the rig?

I've got a 5KVA GE step-down wired for balanced AC output (derate by half) feeding two amps of 500W draw each. The idea is to isolate, so a single household one defeats some of the purpose, but not entirely. 10KVA, single phase transformers are rare and about 200lbs. Most that size are 3-phase.

Noticed a 5KVA Sola MCR on Ebay that does regulation and harmonic filtering but you have to be careful not to exceed the rating of these type, even more so than "regular" ones. Haven't heard of anyone doing a center tap on these, probably because of the price.

Rhyno,

There are many benefits to proper selection and installation of iso transformers in your system. Besides reducing noise and creating a blacker background, I have found they eliminate grounding issues and the need for any further PCs, and make the system much less sensistive to cable/wire swapping.

See my system page below and the pictures and diagrams.

Here are some keys: Balanced configuration is OK but not necessary. Iso must be iron core (the heavier the better), and rated 2-3 times your peak power demand. Follow electrical codes for a subpanel and grounding.

The Mac 501's (each) require 6.6A @120V, 50/60 Hz.

Zargon:
A very nice installation. I tip my hat to you.

Rhyno:
The 'archtecture' page on Zargon's system displays very clearly the guidelines that are spelled out in the Topaz (Square-D) documentation. The only variation that I can see is that Topaz states that (if possible) it is preferable (regarding the downstream ISOs) to place them as close as possible to the load component.

For a look at another system that utilizes a configuration in line with what you described, look at:
http://forum.audiogon.com/cgi-bin/fr.pl?vstrt&1041994460.
Lak uses double 5KVA ISOs (one per 120V leg) feeding his sub-panel.

You might find it helpful to search old threads on this subject. Though he does not post anymore, the past expert on this subject was 'Sean', who was a strong advocate of multiple ISO combined both downstream and upstream of a sub-panel. Sean was also an outspoken advocate of putting further isolation circuitry in the 'bells' of the ISOs.

I am using multiple small ISOs (just like the single that Zargon uses to feed his CD). I have found that some components really shine when placed behind an ISO, and some do not seem to care.

If you can swing the power company to do a three phase install on your home, you get your own dedicated 15 KVA transformer and (if lucky) you will be the only one in the neighborhood on the transformer.

I did this, took a lot of time with a TXU supervisor and I had to "prove" I needed it. In my case the photo studio on the back of my home. Probably a big stereo with multiple breakers might convince them too.

While you're at it, the 750 Amp trans socket meter base is a huge upgrade over conventional power meters and as a bonus, there is no provision for trans socket to be digital (at least not in my market).