Last Friday I had the opportunity to compare my Metrum Octave to my buddy's AMR DAP-777 in my own system and the results were somewhat surprising. The Metrum had a more forward presentation and was a bit more textured while the AMR was sweeter and more laid back. Generally speaking the AMR was preferred with acoustic or simple vocal driven stuff (i.e. civil wars) but I actually preferred the Metrum with blues, rock and male voices!
In both cases the differences weren't huge and as my friend put it, the two units were too close for comfort.
The transport was my Bolder modified Squeezebox Touch with Bolder (music railed) PSU. We're planning on doing the comparo again at his house with his rig, and the transport will be the LampizatOr Transport (heavily modified Sqeezebox Duet with tube spdif out).