Another thing to consider is the audio distortion caused by the internal power amp. Since all the electronics in your receiver shares the same internal power source, during loud volume levels, the current draw from the internal power amp may "starve" the other electronics of power. Ever notice the illumination lamp in the receiver flickering to the beat of the music when it's cranked up? My Blaupunkt did that before I installed an external power amp. Food for thought.
