I am looking into getting a stereo system, with a pair of speakers and a stereo amp. The speakers I'm considering are Magneplan MMGs, and for an amp Cambridge Audio Azur 540A/640A. However, the amp doesn't seem to have a subwoofer output - is this something to worry about? I had been thinking of getting a sub to complement the stereo speakers. I already know the amp sounds great, but should I look for an alternative that has a sub output?