I agree with what you said about competently designed amps; however, in entry level to mid priced receivers they are few and far between. Also, there wouldn't have to be "major" differences in frequency response for audible differnces to exist. I'm not sure what receiver you use, but I highly recommend reading up on amps further (also check out Alan's article on amplification) and actually trying an external amp John if you are intersted to find out how mediocre most receivers internal amps are in producing clean clear sound. Good luck bud!

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