15 SG 450 Polk Audio issues HELP

So I have a new to me SG with the Polk system. The right bow speaker is operating at 20% of the volume of the left and same for forward left speaker in the main area operating but at only 20%. All others are working normally.

I swapped speakers same result. I tried a new direct wire to the amp ... same result. I’ve muted and unmuted all the zones. All zone volumes are cranked up. I’ve tried isolating the speaker and the fade balance does nothing.

I’ve swapped wires on the amp to see if it was the wiring or short or bad Chanel on the amp. Nope.

So on the speakers .... there is a box that the amp to speaker wires go to then it branches off to 4 wires. A + & - to the main speaker and then the tweeter but my question is.... does this box do anything else or does it have anything to do with the zone controls?

A little education here please and any suggestions.
It’s not a deal breaker but it’s just annoying it isn’t working as prescribed.

It’s really odd why this isn’t working properly.

Thanks.

The little box is called the cross-over. Its what directs the musical traffic to the mid-bass and tweeter. its vital component.

If what a mid-bass and tweeter makes no difference, then you swap the speaker wires at the amp, from a channel that the speakers play normal over to a chnl thats not normal, whats the result, did the quite speakers play loud and the loud speakers now play soft? Or quite speakers still played quite after now being wired to what was a known good amp chnl?

RCA inputs can be an issue, The zone controller can be an issue. The amp can be an issue, or possibly an amp setting got bumped.

Thanks Michael. More troubleshooting tomorrow and I will report back.
Really appreciate your time and I will follow up.