Mobile Fidelity's two-LP, 45rpm reissue of Miles Davis'is one of the most eagerly awaited audiophile jazz reissues, which may seem strange given how many reissues already exist. Yet the 1959 album is that rare thing in any art form: an accessible, popular work (it's the best-selling jazz album of all time and continues to sell thousands of copies a year) and also an artistic breakthrough (marking a shift from harmonies based on chord changes at set intervals to those loosely patterned on scales). And Columbia's original six-eyes stereo pressing, miked by Fred Plaut, stands as one of the greatest-studio jazz albums too.

The best KoB reissue till now is Classic Records' four-sided, single-sided 45rpm boxed-set, from the mid-'90s, mastered by Bernie Grundman, who mixed down the original three-track tapes to two tracks while the cutting session was happening. The result (produced in small numbers, now very hard to find) comes very close to the brass, sizzle, and air of the originalfalling just slightly short on tonal richnessand benefits from the discovery, a few years earlier, that the original Side 1 was recorded a quarter-tone too slow (meaning the playback is a little too fast). Mark Wilder, the Sony engineer who made this discovery, mastered a subsequent reissue from a back-up tape, which was recorded at the correct speed, and so did Grundman. Wilder's CD reissue, in 1997, was struck from his own two-track analog mix-down (by this time the three-track tapes were in too poor condition to use as a source), and this is the MoFi rendition's starting point, too.

Repeated delays have marked the release of this album, stirring suspicions that something went wrong, and, while I'm not privy to any inside skinny, the final productthere's no getting around thisdisappoints. The people at Mobile Fidelity insist that they did no fiddling with EQ, but the bass is too strong, and the highs seem boosted too; the cymbals are steely, the horns are one-dimensional. It's not bad, but it sounds wrong. What's to blamethe tape's additional decade of aging? Some mismatch between the mix (as laid down on Sony's tubed deck) and MoFi's gear? some tweak that didn't work?I don't know.

The disappointment is deepened by its anomaly. The productionthe box itself, the fine-grain session photos inside, the super-quiet pressingsis typically superb. And MoFi's other 45rpm reissues of Miles Davis albums from this point onall of which were cut from the original master tapes (perhaps the crucial difference)sound terrific. In the wake of head-shaking over the new Kind of Blue, I listened or re-listened to MoFi's pressings of Nefertiti, Sorcerer, Filles de Kilimanjaro, and Miles in the Skyand, to the extent I could compare them with the original pressings, they are sonically superior. (They're far superior to other reissues by Sony and Mosaic.)

True, the original pressings of late-'60s Columbia LPs (marked "360 Stereo") weren't great to begin with: the quality of vinyl had dropped, and producer Teo Macero fiddled with EQ and other variables on the post-production tapes. Some of Mark Wilder's CD reissues sound better than the originals. (This is especially true of Monk's Columbia albums from this era.) Nonetheless, by any standard, the later MoFi Miles reissuesagain based on the master tapessound wonderful by any standard.

Nefertiti, Sorcerer, and Filles de Kilimanjaro, in particular (the first two from 1967, the latter from '68), are unjustly overlooked albums, outside the world of jazz aficionadi, anyway (inside that world, they're classics, worthy of a place in the top echelon of Miles recordings). By this point, Miles was listening to progressive rock (it's a shame that Hendrix died just as the two were discussing a joint project), as well as Stockhausen and other avant-garde composers; he was moving to electric keyboards and stronger backbeats on the drums while retaining the players of his great mid-'60s quintet (Wayne Shorter, Herbie Hancock, Ron Carter, and Tony Williams). Miles in the Sky starts to get a bit monotonous (and after that the band falls apart), but, even here, listen to Williams' drummingit rocks and swings in ways that no jazz-rock fusion drummer ever matched.

John K. Wood of Mobile Fidelity says the label will reissue Miles Smiles and E.S.P., the quintet's earliest and greatest albums, later this year. That's worth getting excited about.