WakeWorld - tower speakers popping and cutting in and out (WS-420)

hey yall.

yesterday, my tower speakers were cutting in and out after sitting with the engine off for only a short while. it was about 93 outside. the WS-420 was flickering and at one point, the tower speakers would not work at all. I switched the battery switch to the 2nd battery and the tower speakers worked fine. so i thought it was a battery issue. however, i hooked the battery up to the charger when i got back home and it was barely drained. I have 2 XS batteries which are almost brand new, hooked to a 2 bank inboard charger

i have a cadence amp (ZRS 3002) pushing the 2 485's and the stock clarion (APX 480m) pushing the boat ws 650's (6). the in boats worked with no problem while this was happening.

so, after reading numerous threads on here, i've narrowed it down to 2 potential problems:

1. amp to the tower speakers got too hot (i have it mounted against the wall in the bow wing seat area and had that compartment packed with stuff, although nothing was touching the amp, i've never had that much stuff in there.

2. tower amp was not getting enough volts - i have the WS-420 power and ground wires tied into the amp's screw terminals for the power and ground connections coming from the boat batteries.

any thoughts?