This is a WILD GUESS and might be TOTALLY WRONG. But the experts will correct me.

What I am thinking is that if you are using a standard 1/4 inch cable (Tip/Sleeve) to connect from your BIAB source to the L1...or your mixer...then the stereo will be summed in that chord and mono will hit the Li or mixer.

But if you go OUT from the BIAB source with a TRS cable then the sound from the BIAB source will be carried in stereo by the TRS cable into the mixer or T1.

I am reasonably sure of what I'm talking about SO FAR.

But where it gets tricky is whether the "sum to mono" problem will actually take place when the stereo signal hits the L1 SPEAKERS.

What I mean is...here's the question...Is the erosion of sound quality caused by summing a stereo signal into a MONO CORD? Or is the same quality lost because you are hearing a stereo signal through only one stack of speakers???

OF COURSE, you don't get stereo SEPARATION when the sound is heard out of one speaker stack instead of two positioned to the left and right.

But I WONDER of the Bose Line Array speaker technology compensates for that lack of physical separation. I haven't had a chance to call Bose tech support to ask that question yet.

So I just throw out the above as raw meat with the issue being...If the sound leaves the BIAB source via a stereo cable and goes into the L1 is there still a "sum to mono" sound quality problem given the Bose Line Array speaker technology??????

Finally, I know for a fact that there are component devices specifically used when summing a stereo signal to mono. A Google search will return a zillion hits. So MAYBE that is a workaround.

Best,

Jim