Unless you need the MHL feature of the new VX-x75 line (look it up), you might instead look for a deal on the RX-V473. The 473 is last year's model that's one notch higher than the 375, and the 473 (and 475, for that matter) have better, more powerful amps than the 375 (and likewise the 373). I don't see any awesome deals on the 473 at the moment, but if you do, jump on it.
That being said, the 375 will totally play music and movies through those Polk speakers. It will be fine.