I have seen some QC issues and the "cheap" jumpers come up on www.audioreview.com, but I guess that's what the warranty is for. Anyway, I'm curious to know if you are using a sub with the M80's. I'm expecting that you aren't. Also, when you tested the M22's and the C370, did you use a sub to fill in the lower bass? In my current setup, I'm using the M22's and an EP125 and even with an old Kenwood receiver they don't sound weak or thin, but they do need the sub.