11 x 15 room is not extremely small, but I think that an amp in the area of 80 to 100 watts per channel will do if you are only using it for 2 channel applications. I checked one site and that site (Audio Advisor) has the Adcom that pushes 80 watts per channel 8ohm load and 125 @ 4 ohms
here and Parasound for much more
here. Note the prices which exceed your budget. Like I mentioned earlier, you may want go used or refurbished. Good sound doesn't necessarily require high power.