Hi, I only have a 2.1 sound system Sony f200 with sub. Im ready to upgrade to a 5.1 surround sound as i want HD sound. On a tight budget so have decided on Sony amp dh800. Wandered if i could use the sub box from my 2.1 system as am happy with the base, or do i need to buy a brand new sub. Also what speaker wire do i use to connect speakers to amp? Thanks for your help.