joe, a bit of history on these amps "Vibration Technology was a company founded by Hari Ghandi and operated in the 70's and early 80's in Ontario. Hari didn' want his circuits stolen so he used unmarked components in many places and didn't issue schematics to the public, or even techs, he figured they were well enough made that they wouldn't break down and repairs would be unnecessary. The biggest problems with these amps were all the aluminum parts that gradually oxidized , particularly pots that were grounded to the aluminum chassis, but a simple cleaning would usually solve the problem. The entire 140 series used the same power amp, it was connected by a 9 pin plug to the various models of pre-amps which were mounted to the front of the cabs. Hari used his own design for the distortion effect, and no matter what was said to him, he would not change it. Most people didn't like the sound, and this was the greatest criticism of his amps. on the other hand there was no shortage of pedals available and the amps themselves were solidly made. The cabs were solid and lasted forever, even using less than premium quality speakers. The biggest drawback to VT, though, was that they wee gray, and during the hayday of heavy metal, everyone wanted black." from here. While I am waiting to see if I get a manual for the SL140, but I do have the one for the VR-140. Just want to determine the difference in wiring. I attached an image ( from here) of the pinout of the XLR to various other adapters. Hope this helps. Good luck.