What you're trying to do can actually be done with an effect (note: the effect is buggy and it requires the 0.3.7 beta). When using the effect, the clicks disappear.
However, strange things happen when you cross the barrier of H1F...
Yeah, i was just thinking that the pop was probably the mod table being re-uploaded, which could be skipped if it were an effect.
So... that's interesting that it has an effect. (Why is it H though?)
Here's my earlier example redone with the H. The phasing problem is still there (the mod unit really can't make an accurate enough sine), and it wigs out at H20 but I think that's due to a hardware limitation. Even the effect at H1F is kinda weak.
Hmm, Zelda 2 FDS has some high frequency modulation effects. Death sound etc. It's still in the realm of "weird noises" though, not a careful FM synthesis or anything.