I have a non-Bose (base) headunit, and I have replaced the front speakers with Infinity Kappa 60.5cs component speakers and the rear speakers with Infinity Kappa 62.5i. The speakers are very nice and sound great, but I am wondering how much I am missing without using an external amp. I like the natural accurate sound and not the glass shattering bass, so I don't plan on adding a sub. Should I go through the hassle of adding a 4 channel external amp with speaker level input? (I already used the connector on the back of HU for an external CD changer, so I can't use a PAC converter to get pre-amp output) Do you have any recommendation? Or I won't hear much difference with or without the amp because I hardly crack up the volume?