FWIW, I occasionally send CDs to Stebbings or Software Images to be duplicated onto pressed CD's. They accept CD's written at only 1-2x. They 'clover check' (whatever the heck that is) all CD's before making the glass master, and they find that 4x+ contains too many errors.
I also find with the pitch-shifting CD decks, (like Pioneer CDJ's, for beatmixing/dj'ing), that anything written above 4x sounds much more digital when using the pitch correction and jog wheel. I don't know the technical reasons for that. But if you heard it, you'd agree. That's not to say that I can't write an audio CD at 32x which plays quite merrily in antique home CD player and sounds fine. But for flash trickery and audio stability, it seems slower is better. Hope this blah helps someone. Steve
