Don't do it! The GFA555 is already putting over 200 watts into each speaker! Bridging will make each amp "see" a constant load of 2 ohms or less! NO GOOD! Distortion will double, as will current. Too much stress (heat) on the output stage transistors! Stick with ONE amp! If you desire louder SPL's get a more efficient pair of speakers (hint: JBL 100's).
Adcom GFA 555 II
Any advice on running a pair of Adcom GFA 555 ii bridged with Magnepan MG/12QR i am currently using one and was considering picking up a 2nd one, are there any benefits? can they handle the 4 ohm load bridged as i’m sure when pushed they dip pretty low in ohm’s or is this a bad idea?