I bought my Sharp MD-MS722 about 8 months ago and after using it for a while I started hearing the sparkling noise in my recordings, it sort of made me think that Sharp was a bit crap for a while, but then I just thought to myself that ATRAC isn't perfect. I told my cousin Colin my findings and he told me that I was full of crap, but I still said that I heard some sort of funny noise that I had never heard from anything that was recorded on his MDS-JE510. I tried to convince myself that I wasn't hearing this sparkling noise but I just couldn't do it, listening to my MD-MS722 through the earphones made the noise sound very clear and I just couldn't get around telling myself that it wasn't there.
So a couple of months back Colin got sick of me saying that I could hear a difference so he sat me down in front of his stereo and did some recordings using my MD-MS722 and his MDS-JE510. As I listened to snippets of songs I would write down which recorder I thought it was. The volumes and everything like that were exactly the same for the 2 units as he was recording digitally anyway (and the MDS-JE510 doesn't have digital record level control). I picked out some of Colin's music that I thought I would probably hear the sparkling noise on and then he did his recording.
For some of my answers I really wasn't quite sure of which unit the music was recorded on so I put that down as my answer (This is because the song didn't contain the right sounds to bring this effect out). I remember now sitting there and hearing the songs playing, and some of them I remember laughing to Colin and saying "That is most definitely Sharp, can't you hear that noise?" But he says that he is unable to hear any differences as his hearing isn't what it used to be.
Colin went through and compared my answers and I think I was right for about 80% of the answers and most of the other ones were ones I had answered with a "?". I seem to be the only person out of everyone that I know that can hear the sparkling noise in Sharp recordings, but it doesn't bother me at all, I still swear by my Sharp MD-MS722, it is a beast (i.e. great. -eaw). I also use an MDS-JE520 at home to do recordings and I believe that the Sharp's recordings have a crisper sounding top end.