I just got my HTR-5650 wired up tonight and I'm not getting quite the sound from my 6 year old Technics CD player was getting before with my old Sony reciever. The sound from Directv is fine. I don't have a subwoofer and I only have four speakers hooked up at the moment. Do I need a subwoofer to go with my Athena F1's I'm using as the main speakers? Maybe it's just me, but the bass just doesn't seem there.