That was one of my first boards.
Long sold off and gone..
I do not recall having any issues driving
7506s with that hp amp.
If your trying to drive more than one pr.
that could be your issue.
It is not meant for that.
Set up a real hp system for multiple users.
I will say that I had MANY, MANY issues
with the construction of that board and
everytime I had it repaired it came back with
I did like the sound alot though.
Suprisingly cool eq if memory is correct.