I am think about getting a pair of Q Acoustics 2020i speakers and a Marantz PM6003. The PM6003 does not have a Sub output. I might add an active sub at a later date if this system is lacking in bass so would this work, Xonar D2 front out to Marantz PM6003 and bass/centre out to an active sub? If not how would I add a Sub to this setup.