Certain pseudorandom number generators (e.g. linear congruential generators) can be reverse-engineered from their output. And for any generator with a small enough seed-space, if you know the generator used you can exhaustively search for the seed which produces the known output. On the other hand, there was a lot of work done on cryptographic generators which are provably as unpredictable as the underlying cipher is uncrackable. And various hardware generators have been proposed whose randomness is guaranteed by quantum mechanics. If I were designing something where real money was riding on the outcome being unpredictable, I'd go for something along those lines.

But for shuffling music, a decent LCG properly used really ought to be good enough.

--John