I had the same issue.I just got a new Music Hall a70.2 integrated amp and Martin Logan Vista speakers.My MH integrated has pre outs that the manual says can be use to hook up a sub.I had a old paradigm sub that only has one line level input.So I used a y adapter to combine both Right Left into the sub.It worked but made my main speakers mono.So I just use the right preout into the sub.This sounds decent but not perfect.I am waiting on a new HSU sub with right left inputs to do it right.So for me using the y adapter made my new integrated mono.
Stereo sub out to mono, is it safe?
My new integrated amp has L/R sub output and my sub only has a mono input. Is it safe to use a Y adapter to sum the L/R output to the mono input or will this cause a short? Thanks for your insight.