I just received my M2tech Evo from TweekGeek. Ships w a regular 9V wall wart. (I'll upgrade that asap).
Comparing it to my HiFace - the Evo is a significant step up in SQ. I run it straight into my PS Audio PW Dac. With the Hiface, there was no contest - my PWT Transport had way more depth, wider soundstage and more bass. With the EVO (Illuminati D60, XLR), the difference between the Transport (running I2S) into the PWD becomes MUCH smaller. (So much that my Transport is up for sale -lol). This is without "break in" and the standard wall wart.
If you have a fairly resolving system and running a HiFace, I would recommend giving the EVO a try.
Have you had a chance to try a battery based supply? Battery supplies have been known to improve the output signal quality of such devices.
You notice a major upgrade from the Hiface to the Evo?