I have 2 subs, so...One for each sub???
No. You have one LFE signal coming from the player and going to the 990. The two subs connect to the 990, but the player is providing a single LFE channel that the 990 then combines with other signals derived during bass management.
Also do you need to use a digital connection for SD DVD watching as Camtah has posted?
You don't
need to, as the player can decode Dolby Digital and DTS, but I generally have used a coaxial or optical connection for standard DVD's.