I've bought this for a specific reason.
I Run 2 BOSE L1s with B2 subs.. and use a Mackie DL806 desk..
I needed only to have one BOSE system in a venue for an event, but needed more inputs than the BOSE Tonematch had.
I used a lead from 2 - XLR outs (desk) to a Stereo jack in for the BOSE PA.
I got such a strange sound, like a crazy reverb and low volume levels, but had no reverb on the desk. I ended up using just the left channel, wasn't happy with the sound that night.. something was missing.
I looked into why and found that, the lead doesn't 'SUM' the outputs to create a clean balanced signal.
Hence why I've bought the ART Splitcom Pro.
I now should be able to have a stereo signal 'SUMMED' into one lead.
I can guarantee someone else has had this problem.
Hope this review will help you.