A few points RE: AV Reciever vs Integrated Amplifier

Ok I know its a long ongoing debate as to which out performs the other when regards music, but.........

In previous comparisons I have noticed a dramatic improvement in Stereo music reproduction when using an integrated rather than an AV receiver for amplification.

However,

Use an AV receiver to listen to a Music Blu-Ray in DTS -HD Master or Dolby True HD and the results are sometimes, well gob smakingly brilliant. This obviously is due to the source as much as anything

So when using these HD formats the AV amplifier can make the speakers perform at a level which matches, nay, beats into the ground the Integrated amplifier.

Please enlighten me?