I am building a new HT setup for a friend. Room size is 20'x14' with 12' high walls. The equipment bought is Onkyo 809 AVR, Klipsch RF-82 II, RC-62 II, Yamaha Surrounds, Klipsch SW-115 sub, Samsung blu-ray, Samsung 60" LED screen, and a media hub to play mkv files. The setup will be 80-20 movies-music. The main listening positing is 19 feet away. According to the maths I did, keeping in mind the speakers' sensitivity, I think Onkyo 809 is more than enough to easily drive this setup to 75dB spl with roughly 30dB of headroom. Since I am into HT craze for only a year and a half and may be wrong, I need advice on whether this setup requires external 2-channel amp for the mains. I can get an almost brand-new very sparingly used NAD S200 stereo amp for around $1000. I know it's an old amp, but it sure is a monster. But I am being skeptical if I really need that much external amplification keeping in mind I will be crossing the mains at 80Hz for the newly launched Klipsch SW-115 sub , which has 400 watts of continuous power and 800 watts dynamic headroom to deal with the power hungry lowest frequency spectrum. Loudness is not my main concern. Will I get any sonic benefit adding NAD S200 to this setup?? Your comments are welcome.