Tims, I'd suggest that you stay with the Pioneer 45TX. You'll get a very powerful receiver with the MCACC for setup.

For speakers, the M22s with the SVS sub(but the 25-31PCi, tuned to 22hz by Tom at no extra charge, should be plenty)would be excellent in your size room. I haven't found that a bigger speaker necessarily has a "bigger" sound, especially if the sound level isn't extremely high. As is my usual preference, I would use a vertical M2 for the center.

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Enjoy the music, not the equipment.