Hi Zac,
Yamaha is quoting misleading specifications. First, ignore the "Dynamic Power" ratings. Those are totally bogus, measured with no regard to distortion in order to artificially inflate power ratings and impress naive consumers. You could expect that the distortion of those dynamic power ratings would be in the region of 20% or greater, which would sound awful (distortion with music programming begins to become audible with certain instruments at levels greater than 1% THD.)
Note also that with Yamaha's multi-channel power rating, it is not stated how many channels were driven to yield the power measurement and distortion measurements. You can assume it's likely 1 channel driven, not 7 channels.
The Outlaw Audio quoted specs are much more honest and informative. They specify how many channels are driven to yield the power output figures and distortion levels, as well as the frequency range over which the power output is measured. (Often power output is just measured at a single frequency-- 1 kHz-- in order to get higher power output ratings, rather than over the entire frequency range, 20 Hz - 20 kHz, which is much more rigorous test of an amplifier).
It's clear that the Outlaw is likely capable much cleaner high-output power than the Yamana (it's anyone's guess what the Yamaha would produce if you measured its power output with all channels driven; it would be a great deal less than 140 watts per channel, likely half that figure or less).
That said, it would depend on what size of room and at what loudness levels you'd be using as to whether you'd hear a difference in sound quality between the Yamaha receiver and separate power amplifiers. If you pushed playback levels to the point where the Yamaha's internal amplifiers began clipping, producing high distortion, you'd certainly hear that.
Regards,
Alan
