\rHi Steve:
The AMP300 with the Pre One are a great combination. But you will have an issue connecting your passive sub woofer unless it has an internal passive crossover. The AMP300 will be plenty to power your two pair of speakers and your multiple sources connected to the Pre One. But check out the SMP250 a dedicated Sub woofer amplifier needed to drive your passive sub woofer. It would help to know what two pair of speakers you will be driving as well as the passive sub woofer. Maybe you can let me know what components you have (Brand and model). tim@osdaudio.com, then I can be more specific. It also seems like you have a couple more input options including the fourth input on the pre one and a second input on the AMP300.
TL/4817\r