I think that's what it is, unfortunately. A friend tried it on his, same hiss, same frequency, and I tried it on another friend's Nakamichi cr-1a, same. I just don't understand why they sound so much better on a much crappier player.....%$^%$*%&^$%$!!!!
The nice thing, is that, w/ all the tapes, there's a nice , "pure" noise profile right at the very beginning, w/ no chatter or music mixed in, so it should make the removal process a bit easier, but I tend to err on the side of not removing noise, since, invariably, it will remove some of the sounds you want, as well.....