If I recall correctly, didn't Bob Lee say in a post one time that this wouldn't be recommended (or at least would not help) when using QSC amps? Or switching amps in general?
Ah, found some posts from that thread:
"The Rat method works to squeeze a few extra (and certainly welcome) watts from amps with traditional power supplies. There is no benefit when the method is used with switching power supply amps such as the PL and PLX."
and:
"There is less benefit also if the amp is a "dual mono" type, with a separate power supply for each channel, even if the supplies are conventional, because the reservoirs are separate also.
The reason for the amps with switch-mode supplies not gaining headroom from this techniques is that the primary reservoir is before the power transformer, and it provides energy to both the positive and negative supply rails."