Hi Matt

I've been waiting for someone else to reply because I don't have tested answers for you...I guess nobody else does either.

You should be able to build two Zkit1's, each in monoblock mode, and use only three transformers.  But I have not done this (yet - are you reading this Chris K?) and I hesitate to throw out answers that might not be 100% correct.

That said, the power transformer should be easy, as there are not that many options available from Edcor.  XPWR137-120 should certainly work, its the same voltages and more than double the current  in both the high voltage and the 6.3 heater voltage.  At $77 its quite a bit cheaper than two of the Zkit1 power transformers at $58 each.  

The output transformers are a bit trickier.  Be sure to use a single Zkit1 per channel, bridging the R and L channels of a single Zkit1 - DO NOT bridge the R channels of two different Zkit1's to get your R channel.  I think you can just parallel the two output tube plate's and drive a single output transformer without any issue, but I'm not 100% sure.  You are going to want either the 5k (GXSE10-6-5k) or the 2.5k (GXSE10-6-2.5k).  My best guess at this time would be the 2.5k but I could be wrong and you really aren't going to know until you try them and look at the results with an oscilloscope, so good luck...you might be better off just buying four of the stock GXSE10-6-8k's, driving each with a single output tube, and then wiring them in series (2 per channel).

Let us know how it goes.

DanK

When converting a ZKIT1 to mono operation, would it be possible to combine the two inputs (now Y-jumpered together or something similar) down to one gain control potentiometer?
If so, what impedence value changes would I need to modify for input matching?