Vince11281 - I'm glad you are enjoying your Mac amplifier. My unsolicited advice is leave well enough alone and enjoy what you have. I just bought the MA8900 and unfortunately, I had the opposite impression. I've always loved the look and feel of Mac gear and I wanted to treat myself to an "heirloom" amplifier, so I bought the MA 8900 without hearing it first (yes, a big, dumb mistake I know). I got it home, hooked it up and I was completely let down. I sold my Hegel H360 to fund the purchase, and to my ears, the Hegel is vastly superior in sound quality. All of the subtle detail, air, liveliness is gone with the MA8900 compared to the Hegel. To me, the MA8900 sounds bloated and slow with a strange nasal quality. It makes me sad every time I turn on my stereo now because I can't hear a lot of the musical information that I KNOW is there in the recording. I find myself turning up the volume thinking that somehow it's still there, just at a lower level. But it's not. Everyone's taste in stereo equipment is different and we all value different things. I've learned the hard (and expensive!) way that the "warm" Mac sound is not for me. On the one hand, I absolutely love the look and feel of the MA8900 and it looks awesome in my living room, but I'm also turned off by the sound. So, all of this is to say that if you've found your sweet spot with the MAC6700, stay put! Don't change for the sake of change because you might be disappointed as I was.
Oh, and for reference, I'm using Harbeth Monitor 30 speakers and an Aurender N100H like you. I love both of them!