Parts express HT speakers HTS-1200B

Is your plan to hook those up in place of the Z-680 5.0 speakers on the back of its sub, or do you already have a HT receiver?

Most people recommend as a very rough rule spending no more than 1/3 of your budget on the receiver, then about 1/3 on a sub, and the rest on speakers.

You an pick up an inexpensive Onkyo receiver, factory refurbished with factory warranty, from accessories4less.com for around $150. Combine that with the Energy Take Five, and you'll have much better audio quality. Then save up a couple of hundred for a sub.