I've owned a JV1080, JV2080, XP80, XP30, XV5080. Of those, the JV2080 had a terrible problem with this - I sold it and got an XP80 and it didn't have any trouble.
All Roland synths have a noise gate that operates and you can hear it if you listen really close.
Even my XV5080 has noise while the note is playing (imagine that :-) but you can hear the noise gate close off.
I called roland about my JV2080 and they gave a lame excuse, better DACs blah blah blah, yeah right, higher quality converters sound worse - I don't think so.
I think they just screwed up something in the JV2080 and XP60. I don't hear this problem in my XP30.
Daniel Bailey
http://www.mp3.com/danielbailey1