Yamaha - NS-SW050BL 8-Inch 100-Watt-Max Powered Subwoofer - Black

You should have no problem after you locate your receiver’s input bank, and subwoofer input port. I’m like you with my family room system (really big TV): I pump audio from any source to 13 speakers and 2 powered subwoofers through a flagship Denon. Your 400w should deliver just fine, especially with power from your subwoofer pulling up the audio it processes. Good luck and have fun! Brian in Colorado

Don't know what you mean by a good size loft. I have it in a 15X15 Bedroom and it adds more than enough bottom end! Very happy with it's performance.

Yes you can and the Yamaha Sub delivers true bass, very rich and deep frequencies.

As long as it has an RCA plug for a ‘powered’ su-woofer.

The port needs room to breath, right up next to the wall will greatly diminish your sound. The manual shows the best position is angled in towards the listening area, not straight forward.