Originally Posted by Tweaked05
I have read that since most receivers are rated at only one channel driven, if you offload the front speakers to an outboard amp the receiver will then be able to provide more power to your rear speakers. Would adding an amp like the Emotiva XPA-3 provide the same benefit to my HK AVR 354? Or does the HK have separate discrete amps for all channels?
Yes, the AVR 354's 7 amplifier channels are all discrete.
The 354 was rated 75wpc with 2 channels driven continuously. It's EU counterpart was rated 70wpc with 2 channels driven, but 65wpc channel with all channels driven
continuously. (All specs 20hz-20khz into 8ohms @<.07%THD) This should provide a good indication of the 354's all-channel-driven performance.
Like several generations of their predecessors, the 254/354 featured a dual secondary power supply. One supply driving the Front Left/Right and SBL/R channels, and the other the Center and SL/SR channels. Even when demanding program material is taxing the front L/R channels, the center and SL/SR channels are not impacted.
The models which have succeeded the x54s and x550HDs lack this over-design, including the x600s and x650s.
That being said, while adding an external amp to power the front 3 channels will leave more power available to the SBL/R and SL/SR, I strongly agree with jdsmoothie
's reply above - in most situations you will likely see little improvement unless you are pushing the receiver to it's limits.
What is the impedance, sensitivity and frequency response of your speakers? Do you typically listen at high volumes? What do you have the crossovers set to?
If you are currently running your speakers full-range, just using the receiver's bass management/crossover settings for each channel (even at the lowest available 40hz) will take a big load off, letting the sub handle the lower frequencies.