Rick, at the risk of belaboring the obvious, if you are still having the VP150 problem, with the volume set at a level which will safely allow you to do so, put your ear right up to each driver to see if the "pop/snap" is in all the drivers, or just one specific driver. If it's in all, then the problem may lie elsewhere, like a speaker wire, or receiver channel (unlikely). If it's in only one, then you'll have the problem localized.

Jack

"People generally quarrel because they cannot argue." - G. K. Chesterton