DIY Noob - Assistance Please

Hi Guys,

I'm new to this forum, and HT but not new to audio. I have a few quick questions regarding a DIY Subwoofer Setup, Selecting gear and such.

Currently my home theater consists of a low end Sony Receiver... Soon to be replaced by an Onkyo 806 or Yamaha RX-V1800. Polk RTi8's and RTi4's for surrounds and I'm looking to upgrade my sub from the tiny 8" Sony that came with my receiver.

My question is mainly regarding an amplifier and setup instructions. I have searched and I'm looking into 2 separate styles of amplifiers... I was looking at the Elemental Designs LT1300, O audio 500w as well as a Crest FA901 and Berhinger EP2500/1500.

I'm not sure what subwoofer I will run, I have a few laying around from previous car audio installs. Elemental 16ov2, 4x EQHS12's 2 Adire Brahma 12's and a couple others.

If i was to go with the Berhinger or the Crest FA901 what would i require to hook the amp up to the subwoofer output on the Sony receiver. Would i need to run a BFD? Or would a direct connection suffice?

Any suggestions would be appreciated.

Thanks,
Steve