Here's a review copied from Hi-fi Choice
Trust Sony to reinvent practically everything it is involved with at some time or another. In this case it's not the champagne gold finish, or the wide (280mm) shoebox presentation, or even the top-loading mechanism, which is surely a gimmick, albeit an impressively implemented one - a veritable tour de force. No, the headline novelty here is the variable-coefficient digital filter, which has four, count 'em, settings.
There are tonal changes between settings but the principal effects are more fundamental. The standard filter, denominated (0), is a conventional, flat, in-band response filter with brick wall filtering, while (1) is a spline filter, reducing ringing on transients at the expense of high frequency output (see Oasis of Sanity page 15). Filter (2) is a kind of combination of (0) and (1), while (3), an 'analogue' filter, combines elements of (1) with 8x oversampling, simulating a Butterworth filter, giving an impulse response with low pre-ringing, and a characteristically mellow tonality. These descriptions are necessarily over-simplified.
The player additionally offers an extensive array of play, programme and edit modes, with peak-search, fade, index search, plus display on/off switching, two digital outputs, and one of the best stick-type handsets ever.
Sound quality
Each digital filter setting was treated as an entirely separate player in the panel tests, which led to a mass of data, and some interesting observations. Clearly the tricky digital filters had considerable all-round appeal, each outscoring the plain vanilla brick wall filter - number (0).
A pattern emerged when comparing comments from individual listeners. Filter (0) has a "slightly dry upper treble", and "lacked some of the fluidity of the best", where filter (1) was felt to offer "more space" and was also described as "dynamic, spacious, detailed and, above all, honest". Filter (2) came across as "more controlled and energetic," but also "inconsistent". Finally, (3) gave "wider, but more diffuse" imaging, and a suggestion of "brittleness". Another listener talked in terms of "good detail, strong bass" (0), "more fluidly, and plenty of power and projection" (1), "notes are more linear and harmonise more effectively" (2) and "warm and engaging, with plenty of ambience, but some edginess" (3).
My findings, refined over a longer period, suggest that the filters have the effect of altering the proportions of the soundstage, the dynamic relationship between instruments, the mix between direct and reverberant energy, and the overall sense of focus - often quite subtly. Preferences between (1), (2) and (3) often seemed largely arbitrary at first, but there were indications that greater exposure helps sort the wheat from the chaff. I found myself gravitating towards filter (1) which seemed to offer a more expressive quality and better focus, especially compared to (0), and with greater consistency than (2) and (3) - (2) especially.
Conclusion
The idea of choosing filters for the Sony is intellectually unsatisfying - surely there can be only one preferred way? - but pragmatically attractive. Generally filter (1) gave the most consistent, and often the most natural (or at least credible) results, but it is not obvious from an analysis of the comments as a whole that the effect of the digital filter was the dominating factor. Although there were identifiable differences between filters, this was a well-liked player in all incarnations, characterised by strong dynamics, a solid bass and credible imagery. At this price, it is hard to avoid putting intellectual scruples to one side, to award a Best Buy.
AG