I should follow up this thread to clarify WHY I thought the VTL MB-450 was better matched to the Magnepan 20.1 than the 3.6.
The Magnepan 20.1 goes a lot deeper, basswise, than the 3.6 did, and allows the VTL MB-450 to perform optimally, in my opinion, while with the 3.6, I didn't think the speaker was truly letting the amplifier perform at its peak. However, for you (smart!) people who love Headroom, there's nothing to complain about, no matter how you slice it...
I am still an Audio Research owner, and in addition to the VM220 monos and the aforementioned VTL MB-450 Monoblocks, I have added VTL MB-300 and Audio Research Classic 150 to the stable.