been busy. here are a few more details.
The VP4 is a 4 channel preamp. There are only 2 module-faceplates and each of these is attached to 2 early Rocktron/Egnater modules. The top modules share 1 long faceplate and the bottom modules share the other. The module faceplates can easily be cut in half so that each of these early modules can be used independently in other MTS amps/preamps. The boards of the modules have various Egnater markings and appear to be very similar to modern Randall modules. Fortunately, the 2 long module- faceplates are attached to the VP4 in the same way (screw size/location) that Randall modules attach to MTS gear. So there was no need to drill or tap any holes to make the VP4 compatible with Randall gear.
The VP4 does not have an effects loop. There are 2 Main Outs with a Level Control. I simply ran my Main Outs into my rack processor, when I used one.
I'm under the impression that these VP4s were made by Egnater for Rocktron. If that's true, then this unit should be bulletproof (it has been, so far) and selling for far, far more than I've seen them going for. Only because I know I won't ever need another one, I'll say straight-out that I'd pay 4x's more for an Egnater made VP4 (if, in fact, he did make them) than I would for an RM4. Yeah, The Randall stuff sounds killer, but I've just seen and/or heard about too many irritating quality problems with Randall gear.