Every DVD-A release is watermarked. If I remember correctly, one of the 'features' of the watermarking technology is that it must survive mp3 compression, and other bad things too. I'm sure the technology has been cleverly engineered, but at the same time, mp3 codecs are very highly tuned, the aim being to remove everything that is inaudible. If the watermark manages to remain intact throughout a highly destructive 128kbps mp3 encode, then clearly the encoder is not doing its job, and it may be tuned to the point where the watermark disappears. Unless, of course, the watermark is colouring the sound in an audible way, which would be a very sad thing to happen to a format that is otherwise so much better than a CD. I think SACD uses a similar technology, but I'm not sure.