I understand joeinid, in my case the Mac XRT 30 speakers are not very efficient @ 87 DB SPL 1watt @ 1 meter !! So I noticed the AC line monitor dipped alarmingly low during strong impacts of dynamic music passages from DDD/SCAD CDs when the amps were plugged into my living room`s regular AC circuit and I thought the bass sounded some what mushy from what I thought it should sound like. I`m a retired FOH sound engineer and became used to live dynamic sound.. So that helped guide me in my system setup..