So here's where I'm at......
I did a global reset and issue persists.....
There seems to be no reason at all behind the output levels of the amp models when used in a 4 cable system. At first I thought it might relate to actual output of the various amp models with lower watt amps being quieter. Not so. The high gain stuff (treadplate, doom, etc.) all works great. The Gibtone and supr 0 provide enough level to be usable. The PHD, blakface normal & lux, and lot's of others are all very weak. Some can be brought to a usable range by turning up the mixer levels all the way but others need even more like all the gain a studio pre can add after tha mixer.
Any type of real clean tone with any headroom seems almost inmpossible, thankfully I can get a great clean tone from the pre in my actual amp......
But still this doesn't seem right.....should be able to use any amp model with this connection. I mean after all when not using the FX loop and my preamp it is basically a single cable connection direct to my power amp.....
Anyone else have any thoughts?