Well, I received the Walter M2 Blu-spec CD the other day and have compared it to the domestic Bruno Walter Edition 20-bit remastered CD (c. 1995) as well as the more recently issued CD in the Original Jacket Collection box set. Both of the domestic CDs seem to have been derived from the same master, as they had similar sonic characteristics (though the Original Jacket CD was slightly louder). I've never been happy with the sound of the domestic CDs compared to what I remember from the old Odyssey LPs, and this was borne out in my listening comparisons: both of the domestic CDs sounded heavily filtered, especially when the music is at low-to-moderate levels. By contrast, the Blu-spec CD sounded wide open, MUCH more detailed, and with greater presence--it wasn't even close. The Blu-spec CD also had a lot more hiss--an indication that no (or less) filtering was applied--but with a concomitant increase in detail and 'air'. Instruments that were muffled or recessed before have now been brought back out. The organ (probably electronic) at the end just absolutely engulfs the listening room. (It's one of the more ecstatic M2 endings that I know of--now sounding better than ever.) I've always thought this early stereo recording (1958) had great sound for its time, but I hadn't realized just how good it was until I heard this CD--it's comparable to the RCA Living Stereo efforts from the era. If I had to nit-pick, I'd say that it's a little closer-mic'd than I would like, and it also lacks a bit of front-to-back depth, but overall it's a HUGE improvement over the domestic release.
I'm pretty certain that the superiority of the Blu-spec CD is due to a much better remastering (in DSD) and not to the Blu-spec manufacturing process itself (though that certainly couldn't hurt). I don't read Japanese, but there was an indication of "DSD" and "1999" on the "obi strip" of the CD, which I take to mean that the remastering was done in that year. Perhaps this was done in preparation for an SACD release? We'll never know, but this Blu-spec CD is the next best thing.
The only drawback to this CD is that it's available only from Japan and that it's on 2 discs with no "filler". At 3500 yen plus shipping, it's pretty expensive, but if you like this performance (as I do) and only have it on a domestic CD, you really haven't heard it to its best advantage.
Russell