Although we haven't heard any DTS-HD Master Audio lossless discs yet, I'd like to get everyone's opinion on which codec they prefer in terms of theory. Here is how I understand it. First, Dolby TrueHD (being based on MLP) is not backwards compatible with Dolby Digital Plus/Dolby Digital, meaning that if you playback a TrueHD signal on a device without TrueHD decoding you will get no sound even if that device has standard DD decoding. DTS-HD Master Audio is backwards compatible with DTS, meaning that if you playback a DTS-HD Master Audio soundtrack on a device without DTS-HD Master Audio decoding, you will get standard DTS sound so long as the device can decode standard DTS - but at what cost? Let's say "X" is the Master. Dolby TrueHD encodes "X" into a lossless signal which is decoded by a TrueHD decoder during playback. Fairly straightforward. DTS-HD Master Audio encodes "X" into a lossy signal "Y" and stores the information normally thrown away during lossy encoding as "Z". When played back on a standard DTS decoder, all you hear is "Y", and "Z" is ignored. When played back on a DTS-HD Master Audio decoder, "Z" is added to "Y", theoretically giving you the original signal "X" (hence lossless). One big problem I see with this. Since Standard DTS is a lossy signal, it is likely some artifacts will be present in the lossy "Y," however those artifacts obviously can't be removed for DTS-HD Master Audio since the original lossy signal "Y" plays the biggest role (I would wager 90%+ of audible information) in assembling the "lossless" signal. Therefore what you are essentially getting with DTS-HD Master Audio is a signal that is not truly lossless, as the lossy signal is in reality the bulk of the the "lossless" signal and the artifacts in that lossy signal are carried over into the "lossless" signal. Also, despite this DTS-HD Master Audio actually takes up more space than Dolby TrueHD. Despite its appearance of being inferior sonically on paper, DTS-HD Master Audio's backwards compatibility is a massive booster to that format on Blu-Ray as Dolby TrueHD decoding is *not* mandatory for Blu-Ray players. Because of this, studios will hesitate in using TrueHD on Blu-Ray releases, since there will be no standalones that can actually play the tracks. However, by using a DTS-HD Master Audio track Blu-Ray studios can placate both the customers who want "lossless" sound while ensuring everyone will at least get Standard DTS. This has already happened, with several Fox titles set for DTS-HD Master Audio on Blu-Ray and zero TrueHD titles. On the other hand, with HD DVD we already see many TrueHD titles since TrueHD decoding in the player is mandatory on HD DVD. So, while DTS offered higher bitrates that generally resulted in better sound on standard DVD, in the high definition realm their codec falls significantly short of Dolby's IMO. Thoughts?