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

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).

Jeffcott, if by "downstream iso", I assume you are referring to the small 125va iso on the CD dedicated line. That iso, while next to the subpanel and large iso, is only 15 ft. from the CD player. Note that I mounted it at right angles to the main iso to minimize any cross coupling. I have tried the small iso in the room on the CD, and tried it as presently mounted, and could not perceive any difference. Note also that the class D amps in each speaker are on dedicated lines but not through the main iso.