[CM] dac-size limit?

[Bill Schottstaedt]

 > Any ideas if this is a hard ceiling or if there is a way I'm not seeing to
 > get it higher than that?  Even at 256 playback is choppy and gross.

If I remember this issue correctly, the OSX built-in audio devices
have a buffer size of 4096, so if you make the Snd buffers too
large, various things go awry (it plays too quickly, I think).
So in OSX, I made the max 256 (this refers to frames, whereas
the 4096 is bytes).  I took out this check.  If OSX users notice
playback trouble, check dac-size first.