OK, last question (at least for the hour, because this thing is sounding better all the time), Can we use the effects out to the effects return of another amp or power amp input (just using it as a pre-amp) with AND without a speaker load on the head? And would you just be adjusting the gain and not the master? Or maybe not as the block diagram seems to indicate that the master is before the effects send. The master would then dictate the output to the effect send??
Fender explicit supports this with their Bassman line and I have tested it with Rumbles.
This illustration pretty much says it all:
The EFFECTS LOOP is post all user controls.
All the knobs and switches on the "RETURN" amp are bypassed and
all tone, gain, volume, etc. controls are via the "SEND" amp.
On a Rumble 500 combo, the results would be 4 x 10" speakers and a total of 700 watts available. You could also connect extension cabs in the normal way and get, for example, 8 x 10" speakers driven by 1,000 watts.
Plugging anything into FX RETURN disconnects the pre-amp and
all its controls from the power section (per the little red box below)
Here's the full block diagram for the Rumble v3 from the 40 through the 500, both head-only and combo:
________
edit:
Oops! I misread the original question. To use a combo as a pre-amp-only, hook it up using this guide and then plug a do-nothing plug into FX RETURN.
It was difficult to answer your question because your actual question was deeply buried in your proposed solution. In fact, you never really ask what you intended. I THINK you were asking, "Can a Rumble v3 combo be used as a pre-amp only?" The answer is: "Yes." It can also be modded -- via the
eric_B mod -- to function as an amp only or a cab only.
