I interpreted the post as Ron saying that the woofer was better on the PC+...

As far as I know the amplifier is similar other than the power rating -- 525 vs. 300 watts RMS.

M60ti, VP180, QS8, M2ti, EP500, PC-Plus 20-39
M5HP, M40ti, Sierra-1
LFR1100 active, ADA1500-4 and -8