Unique perspective on Marantz PM10 characteristics

I have experienced a unique perspective on the characteristics of my new Marantz PM10 integrated amplifier.  Besides the fact that it operates so much cooler than my previous Class A/B amplifiers and that it can power my B&W 803D4 speakers with ease, I have been able to experience the amplifier using its built-in Reference pre-amp versus a separates Marantz AV8805 HT pre-amp.  The differences were so much fun to compare.  My HT set-up uses the AV8805 to power the front 803's using the PM10 in a by-pass mode. My first few weeks I ran the PM10 integrated all by itself and enjoyed a lush, but well-defined treble without any hint of edginess. On a lark, I decided to listen in stereo by using the AV8805 as a pre-amp. Goodness, the sound this time was more detailed and a more highly articulate treble. I could actually live with either one, but bad recordings, played loudly, really sounded bad with the AV8805.  Using the PM10 by itself, bad recordings, played loudly, sounded much less bad. I'm having a good time flipping back and forth.  My source for these comparisons has been a Rose HiFi 150b connected with an XLR interconnect to the PM10 and an RCA interconnect to the AV8805.