You mean DPCM, not ADPCM. (DPCM is more primitive than ADPCM.) FamiTracker doesn't support ADPCM channels. I think there is an expansion chip with ADPCM, but if so, FamiTracker doesn't support it.
To answer your question, I don't think the problem is with FamiTracker. It sounds like the noise is part of the sample itself, and VirtuaNES and your other NSF players just aren't filtering out the noise.
If you import your samples into FamiTracker at a lower volume, you will probably have fewer problems with this.
for the record, foo_gep in foobar2000 plays it somewhere between the two. the high frequency is higher and not particularly audible.
i think i have had this problem in the past myself, and since i'm so crap with DPCM i never found a sure-fire solution besides just playing around with different samples and volumes (both before and after importing into fami.)
