The best solution in my case was to put my subs in "auto-on" mode, and turn the BFD on and off only when the subs are in hibernation. I have found that in this configuration, there is no pop if the sub is hibernating. Intermittently when the sub amps are switched on physically, they revert to "on", and wait the prerequisite time before returning to "hibernate". In the event that power is lost and then restored, both (an always "on") BFD and sub being "turned on" at the same time may also produce the "pop". Of course, I can be a little over-cautious (or so I'm told)...
Peace... Vader
Louvre attendant: Sacre bleu! ze frame on ze Mona Lisa broke and ze only one left iz too small. Andre, bring me ze scissors!
One sub to rumble them all. One sub to shake them. One sub to humble them all. And in the darkness break them.
The Overlook Theater - Not liable for injuries sustained while laughing.