I own HD600's and auditioned the ASL MG Head DT and the MF X-Cans v.2 over about two weeks at home before buying the MF. The ASL is an appealing unit for the money, but was ultimately too colored (in an overtly "tubey" way, and I'm a tube-amp guy), and a little veiled and not as dynamic compared to the MF (and I didn't pass judgement until I had invested in a fresh set of JJ EL-84's for the ASL and broken them in, giving it every chance). I liked the impedance switch, on-board power transformer with EIC AC-cord socket, and the overall build of the ASL, and would have preferred to keep it over the MF if the sound quality had been equivalent. But the MF was definitively more linear and extended, and just sounded more transparent, natural, and powerful (though the ASL did have a wee bit more "space"). The OTL, wall-wart-powered MF doesn't sound obviously tubey in any way, just neutral, clear, tight, and fast, with plenty of noise-free drive, and the handy loop output jacks are a valuable feature to me which the ASL lacks. Unfortunately though, other than the trademark X-series cylindrical casework, I have come to the conclusion that the build and parts quality on the MF are not as good as I expected. I have had particular problems with the sealed-in-plastic output jack design, wherein the uniquely delicate contacts seem susceptable to deforming slightly, thermostat-style, with the heat build-up from the always-on twin 6DJ8's inside, losing the right-channel signal (I'm currently in need of my third replacement jack). This product could have been even better with decent tube sockets, volume pot (and knob!), I/O jacks, and beefier circuit board and traces - not to mention tube ventilation - all of which were superior on the ASL. I may yet want to try the Berning someday, if I can justify the expense.