Best NES emulator?

[roystonlodge]

(I searched the forums but did not find this topic. If it has already been covered I apologize.)

Does anybody have a favourite NES emulator they're running on the XO?

I've had a devil of a time finding one. I've finally settled on mednafen, which give me good framerates but terrible sound.

I find it strange that I have such trouble emulating the NES since I have almost no trouble with MAME, SNES, Sega Genesis or TurboGrafx-16. What is it about the NES that makes it so dificult?

Thanks in advance!