Output issue with BBE Sonic Maximizer

[VifferMike]

I have a BBE 362NR (Sonic Maximizer with a noise-reduction circuit) in my rack that I run through the effects loop of my amp, per the recommendation of a BBE rep on TB a few years back. I've had no issues with the setup while using it with SWR, Eden and Genz-Benz amps. However, the effects loop on the Markbass TA 501 that I have now is causing some weirdness.

First, there's some noise being generated in the circuit. I can deal with that. But the big issue that I'm having is that there's a marked difference in output level when the the 362NR is switched on and the sonic maximizer is activated versus when the 362NR is switched on and the sonic maximizer is deactivated.

With the maximizer on, the volume output is roughly the same as if the unit was switched off completely, but the tone sounds overdriven (and the sonic maximizer effect, to my ears, sounds lessened). When the maximizer's off (but not the entire unit), the volume is decreased at least 5 dB, and probably more.

Does anyone (especially the BBE reps that lurk on TB) have any insight as to why this is happening? Is the Markbass' effects loop designed differently than the other brands? Did my 362NR somehow fry itself in between my old GBE600 and the TA 501?

I'm not sure whether to post this in Amps or here, but since my effects unit is causing the issue, I figure that this is a more appropriate place ...