Great reply, so thanks for that! I'm a couple hours south of Sweetwater and am planning on making a trip to go through the Z lineup with a particular eye on this amp....and a different power transformer (single tap vs multi-tap speed/comfort design), and a different, smaller output transformer (to accommodate the output impedance curve of two power tubes rather than one), and a different speaker (greenback ceramic vs gold alnico). The transformers and speakers are by far the most expensive part of the amp (next to the cabinet itself, which is exactly the same as the Z Wreck standard), a close second being the aluminum, welded chassis which is used on many of our amplifiers and we can purchase in a quantity that allows us to save cost on that end and make the amp less expensive on the consumer side.
The Z Wreck doesn't have a master volume, mind you. If you are mostly a clean amp sort of guy, this wouldnt bother you. But many players want to turn up the Z Wreck and get that dynamic overdrive at a manageable volume, without being yelled at by whoever, hence we outfitted the Z Wreck Jr. with a master volume.