If you sit no further than 10 ft, for stereo music listening, you should be able to get very decent sound quality. Adding a high end separate amp will only get you more headroom if you like to listen at or near ref level. I have compared the 3400 to my separates, so it know a little about that
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If you run Audyssey correctly, at volume 0 you should get 71 to 75 dB from the main mic position using c scale. The older models seemed to be closer to 75 dB.