First of all, thank you all fellows here for your precious help, in particular MHuss but others too.
The amp is a '79 DR505, which has made its way around the globe sometime ago.... tube fx loop, non-"canadian" gain mod, tweaked values.... well.
Before
![Image](http://www.led-zepped.com/gear/dr505before.jpg)
AFTER
![Image](http://www.led-zepped.com/gear/dr505after.jpg)