BFD output hum -not ground loop associated

I added a BFD 1124P to my system in October. After following the forum threads I decided to play with my settings. I verified and eliminated my ground loop hum with a cheater plug. Temporary fix, I know. Ran REW, found my peaks and assigned filters. I input my filter values into the BFD manually. As I set my last filter, my sub started to hum. The hum is heard only in either of the two BFD output modes. If I set the IN/OUT swith to BYPASS mode (monitoring the input level) the hum goes away. With all equipment powered down with the exception of the BFD and sub, the hum is present. I leave the BFD on 24/7. The hum is still present the following day. So it appears the BFD is the source of the hum. This weekend I powered down the system with the exception of the BFD and my sub. I picked up a DVD which was propped against the BFD. Suddenly the sub started to hiss and crackle. I looked at the BFD and the LED's for both channels were completely lit up. Powered the BFD and sub down and back up and all was back to "normal". As I am in the desert and it is very dry here, could I have zapped something in the BFD with static electricity and caused damage resulting in this hum? I have have not seen any threads describing this type of BFD behaviour. Any insight would be greatly appreciated.

On a seperate BFD topic, I am considering adding the Hsu MBM-12 mid-bass unit. My sub would then cover the 50hz and below range and the MBM-12 would cover the 50hz-80hz range. Is it better to split the LFE channel before the BFD input, utilizing one channel for each unit or to use one input channel and split the BFD output?
Thanks,
Scott

[bobgpsr]

It could be a component in the BFD internal power supply that is failing. An electrolytic capacitor leaked and has dried out. Part of a full wave bridge rectifier failed, etc. Caps are always the most likely thing to fail nowadays. The lower than normal and noisier resultant internal voltage could make the rest of the BFD act flakey.