Will this new gear replace one of the amps you are currently using, or is the new plan to convert your dual mono rig to stereo?
Yes. I am going the preamp + poweramp route now. I just used the other two amps originally to test things out (because I bought a cheap combo for my 2nd amp and tried to integrate with my current head).
There are two reasons for this....my main head+rack of effects includes the head and an 8 space fx rack on top. This things is HEAVY! If I were to use another regular amp head, I would need to get another case. Then, I would be lugging a lot of crap to shows and running cables all over the place. It makes more sense for me to have it all in one rack and wired up. Before integrating the second amp for the looper idea, I would simply pull the cover off my head and rack. Then, I would plug in 2-3 cables from my midi board and hook up the guitar cabinet. Setup was less than 5 minutes. I want to keep it that way. So, by going with a preamp+poweramp in a rack, I will be able to set it up the same way but only have to hook up two speaker cables. I am currently looking into trying to have my fx rack in one case and my preamp+poweramp in another case. That way, I could have one 8u rack for fx/switching and one 8u for the pre/power. Most likely, I will create some sort of patch panel on the back to be able to simply plug cables to connect one rack to the other. Not sure how to do this exactly, but I am researching on it. Anyway, this setup allows me to be able to carry all of my gear myself if needed (you never know when a band member will have the classic 'back troubles' the day of the show!).
Also, thanks for clarifying you want to solo using effects that are different from the effects used on the looped recording. Unfortunately, my position remains the same and I still believe the best way for you to accomplish what you want would be by putting the ABCadabra and Looper up front as previously described and using two independent effects chains, one for each amp. Probably not what you want to hear, but the money you're going to spend on that new preamp and power amp probably would have served you better were you to invest in a few new FX units. Be that as it may...
See my point above...the difference in price between selling my first head and combo to buying a preamp+poweramp is about 1k if I buy used. Yes, that is ALOT of money. However, it is also a much lighter option then you mentinoned. Plus, I am very happy with my current set of effects and don't want to go to the trouble of buying more, integrating them, powering them, and finding the space for them. I like to keep things fairly simple and light.
In the diagram you posted the other day, GCX Loop 2 apparently contains an effect labelled "weird." What exactly is that?
It is a Death by Audio Octave Clang.
Getting back to the diagram, I'm also trying to understand why you've got Loops 1 thru 6 configured as illustrated. Your guitar signal goes into the Gate and from the Gate travels to the Loop 6 In jack. Loop 6 controls a Delay, and the Loop 6 Out goes to the Serial Loop return of Amp1. Your signal then exits via the Serial Loop Send jack, goes back to the Gate and from there it goes to the Loop 1 In jack. Then it goes through Loops 1 thru 5 inclusive, exits Loop 5 and goes to the Amp1 Input jack. What I'm seeing here is, if you took the Gate and all the effects in Loops 1 thru 6 out of the picture, you're basically running your guitar into the Serial Loop, then out of the Serial Loop to the Amp's Input jack. What's the logic behind that?
I am not sure you are looking at it right. The gate is an ISP Decimator Pro Rack G. It has one input/output section to put on the front of the amp for 60cycle hum. The second input/output goes in a serial fx loop to cut out preamp hiss. So, my guitar signal goes into channel 1 and back out to the front of my signal flow in the GCX. Then, my signal flow goes out of GCX5, into my amp. Then it exits out of the amp's first fx loop, which is serial and into the Decimator's second channel. From there, it goes back into Loop 6. In that Loop, I have my mixable delay (so I can mix in the wet signal with the analog path). Then, it feeds back into the fx loop return. That is the only way I could incorporate both items post preamp in series. After that, the mixable parallel fx loop #2 feeds into loop 7. Then, it returns back to the amp. I that fx loop mixed 25% wet and 75% dry. My fx unit is set to 100% wet. This keeps my dry signal pumping through the amp and not being processed through the unit.
So....I am going with the preamp/poweramp option for the previous reasons. Unfortunately, I am going to also have to get a mixer to run my dry signal parallel with the fx wet signals now. Before, I was handling that mix with the knob on my amp. <bummer>. But, I think I can pick up a used Rane for around $100. I've used one in the past and it worked quite well.
I suppose I'll let you know how it goes once I figure out the exact routing. Thanks again!