For the record, my outside speakers are plenty loud; but since there is only a single volume control in the install when I make them as loud as I want; the inside speakers are too loud.
So the issue is adding a separate volume control for each channel, A; B; and C.
I will look around for a speaker level volume control. I think it would be a good candidate for a simple mod that can be located right at the sound system panel.
Lou and Laura with Bella - German Short Hair Pointer
2008 GMC Sierra 2500HD Crewcab SB Allison Duramax
2010 Flagstaff 8526RLWS - Superglide 3300
HAM CALLSIGN - KC3FFW