Klipsch - Reference 12" 400W Powered Subwoofer - Black

If using a low line input it needs to be on the left channel input only. And ensure your receiver settings are enabling the sub to run as such. Hope this helps

Unless you're listening to super bass heavy music or have a 2000 square foot listening room one 10" will be fine.if you want always find yourself wanting more bass the 12" sub will be louder and deeper but also take up more room. These subs have their own amp. Your reciever only sends a signal to them. So you will be fine with either size

I have mine hooked up via LFE and sub out on the back my receiver. By doing it this way, bass management is handled by the receiver and not by the controls on the back of the sub. Just remember that if you choose to have receiver handle bass management, move the cross over dial on back of sub to its highest crossover so that it bypasses the sub's internal crossover and then adjust the gain to a level that is appropriate for your room and speakers.

Yes, Bestbuy is a official Klipsch dealer. You can verify that through Klipsch's site specifically if you choose. I can honestly attest this is accurate. One, I have bought from there an utilized warranty. And that was before I later became employed as a manager at Bestbuy.

Have you tried contacting Klipsch directly? They were very helpful with me.