My Onkyo DX-7555 arrived yesterday, and I had a chance to listen to a few CDs. I tried the two filter options and the clock-rate adjuster with several CDs. Surprisingly, considering that I've lost the top octave of my hearing, the "soft" filter sounded too muffled for comfort, even on one or two CDs where high treble seemed overbearing, so I stuck to the "sharp" filter. Also, I could not hear the improvement
in attack that the soft filter was supposed to bring. With either filter, the starts of notes seemed unremarkable, typical of CD, and nowhere near as good as I remember from the Naim CD5 and better Naim CD players. The clock-rate adjuster had no obvious effect but the instructions say to try it on CDs that sound blurred, and I haven't yet come across such a CD.
Instruments on the DX-7555, compared with my Onkyo DV-SP502E disc player and my M-Audio Audiophile 192 soundcard, tend to sound more vivid and focussed with better pitch, note-shape and expressiveness. I didn't do any direct comparisons because the differences were obvious enough for it to be unnecessary.
Even in the first few seconds of the first CD, Perfume - Complete Best by Perfume, drum sounds that had previously been "thunks" of vaguely discernible pitch were tighter, with satisfyingly clear pitch variation and shape. Throughout the CD the musical significance became apparent of sounds that previously seemed to have been thrown into the mix in a fit of indiscipline. Even distortion effects, which on one track had previously seemed overdone, sounded more precise. What had previously sounded almost like a crackly contact now sounded crisp and raspy.
I hardly ever listen to Avril Lavigne's first two albums, mainly because they hurt my ears. I think of them as "painstakingly badly produced" because they seem carefully worked to sound the way they do. To my surprise, they were a lot easier on the ear with the DX-7555. As before, instruments were more real, music made more sense and distortion was better handled. It seems as if my disc player and soundcard had been freaking out and introducing their own distortion in response to distortion effects.
The next CD I can remember was another badly produced one, Single Hits Collection. Best of Avex Anime 11999-2003, which is a copy-protected CD. On this, similar observations apply,but high-frequency vocal harmonics were unpleasantly loud compared with the DV-SP502E and the Audiophile 192. Nevertheless, even in this case I preferred the "sharp" filter, and the sound was better focussed than I had previously heard.
My tentative conclusion is that the DX-7555 is comprehensively better than the DV-SP502E and the Audiophile 192 but perhaps not by an "order of magnitude" (to be meaninglessly precise) in any one way - i.e. it's noticeably better in almost every way but not to a huge degree. I suspect, for example, that the Naim CD5 would wipe the floor with it.
What this means regarding comparison with the Cambridge, NAD or any similarly-priced player I cannot say...
Update 23:19: Listening to the first CD of the day I've found that the effects of the clock adjuster are noticeable, albeit not useful. I'm not sure if it's the CD or the fact that the DX-7555 has been switched on for more than 24 hours. I expect it might also need some burning in.
Update 2010-01-21 17:51: The sound is still improving. It's a normal sort of thing to happen but I'm a born pessimist, so I'm still a bit surprised! The last two CDs I listened to sounded better with the slow filter. Although I could hear the "roll-off" in comparison with the sharp filter neither CD sounded muffled, and the expected improvement in attack (and dynamics in general) that was previously non-existent is now quite audible. I won't say more, for now, but I'm very pleased with the DX-7555.