John Atkinson has posted a review of the Musical Fidelity M6 DAC ($2999) at Stereophile. His conclusions:
“Musical Fidelity’s M6DAC is a superb-sounding, versatile D/A processor capable of handling high-resolution files via USB, which, along with its smart styling and excellent measured performance, might be thought sufficient to justify its $2999 price. Its Bluetooth capability sounded better than I expected it to, and on all of those grounds I recommend the M6DAC. But with three of its features offering little or no practical utility—the nonchoice between filters; the Level Adjust function, which would have been more useful as a proper volume control; and the de-emphasis Off choice, which might have been more useful as a de-emphasis On, for serial datastreams that lack the correct flag—I can’t help thinking that a more universally useful DAC could have been produced from the same ingredients.”
You can read the full review here.