Anyone here designed circuits using a transconductance amplifier - specifically the 3080E used all over the OB-X

I designed a simple 3080 circuit (based on the chip A6 3080 circuit on the OB-X mother board) that was intended to let me control the noise level on my OB-X using the PWM amount knob. But in just trying to calibrate it I burned up 5 3080 chips and a few transistors. I just don't get it - based on my calcs everything is well within ratings.

I thought there might be someone here that has played with these things that could help me see what I am missing...

Thanks - and happy new year.