Thanks for your reply. When in the Involve and SQ mode there is a constant loud low frequency rumble along with static hiss in the four main and sub-woofer channels (I do not use the center channel). These issues do not occur when in the stereo mode. When the SM V2 is bypassed, there are no such issues.
Also, a loud pop is heard when switching modes
Additionally, loud static occurs when touching or moving the power input where it is inserted into the SM V2.
The quad and sound quality of the SM V2 is most impressive. I have had no problems with the unit whatsoever until these issues appeared of a sudden. Fortunately, I a quad decoder backup but, it is much inferior to the SM V2. Thus, I look forward to getting back to a healthy SM V2.