the rotel doesn't seem to push the speakers very well at low volumeKeep in mind that at low volumes your ears are MUCH less sensitive to bass frequencies, relative to their sensitivity to mid-range frequencies, than they are at higher volumes.
http://en.wikipedia.org/wiki/Fletcher-Munson_effect
http://www.lindos.co.uk/cgi-bin/FlexiData.cgi?SOURCE=Articles&VIEW=full&id=17
Regards,
-- Al