Jul 20, 2008 08:39 pm Well it looks like the XLR on the back of that amp is not exactly a DI output. It appears to be another line output, but is possibly carrying line level signal, which might not be a good thing to plug into the input of the Toneport.
A DI might help you there, although I think you may be adding more noise with a passive DI box. But an active usually will contain a type of pre amp itself or gain boosting circuit which again might not be good.
You might want to look into a line matching transformer. I believe that would bring the signal output of the amp head to a level the Toneport can use.