Thank you Mr Hoffman

[stevehoover]

I just finished building an amp stethoscope  (it works like a charm)! Thanks Doug...this thing Rocks!

I didn't have a suitable donor amp to build it into, so I built a stand alone box per the instructions on the site.
I used a cast Aluminum box and switchcraft jacks.   One useful addition was a custom cable I built with a standard 1/4" male plug and shielded cable to a "Y" with a 12" alligator clip on one side (for my ground connection) and a Pomona mini grabber clip (for signal) on the other side.

With this cable on the input, I can hook up to the amp I'm testing hands free. (I don't need an assistant to play the guitar).  My output goes to a working "clean" amp via standard guitar cable.  I also built a dummy load with a 100w variable ohmite resistor.   

I should have built this gadget a long time ago!!!  It would have paid for itself 20 or 30 times by now.
Thanks again......