My M6 has a much wider and especially deeper soundstage than most of the other amp.s that I checked. The bass is exemplary, and the dynamic reserve is much greater than one would expect from an amp. rated at 120w/ch. It always runs cool, and it provides that non-fatiguing iquid sound that some people associate with tubed amps. However, it doesn't always have the inner detail that it might, and it can get a little confused with complex orchestral music. These shortcomings appear when compared with more expensive amp.s, like the bridged BELs that I had for a couple of days. I've never heard the big optically biased model: it looks gorgeous. If you buy a used EDGE, get the serial number and ask the manufacturer if it's the latest design. Updating the boards on mine cost about $450.
Jan
Jan