u gotta forgive mega , this week i think mega got PMS , next week i will take him go bolevat for treatment 

Neither Geoff nor I could hear any differences between the original PCM track and the TrueHD version, which should be the case, as they’re bit-for-bit identical. The lossless coding process is analogous to “zipping” computer files—it’s simply a function of more efficient packing that loses nothing along the way. With movies, TrueHD typically provides a two- or three-to-one bitrate reduction compared to the original PCM source.

Next, we compared the original to the Dolby Digital Plus version (that codec is found on numerous BD titles, and like TrueHD, is fully backward compatible with regular Dolby Digital decoders). Even on this extremely high-end system, we couldn’t hear any difference between the uncompressed and the compressed. Then, we compared the higher bitrate (640 kbps) that is found on the Dolby Digital tracks on Blu-rays to the original. "Golden Ears" Morrison was able to hear the difference, but I, and most others in the room with us, did not. Each of us had our turn in the prime listening chair, and couldn’t know the origin of the clips or their order of presentation.

The shocker came when we compared the lower 448 kbps Dolby Digital DVD bitrate to the original. There was an audible difference, but it was only ever-so-slightly noticeable (and this is with a high end audio system in an acoustically controlled environment that is so far beyond what typical home theater systems are capable of resolving). There was just the slightest decrease in presence with the DD version, not exactly a softening of the sound, but just a tad less ambience and a similarly small tightening of the front soundstage’s depth. Quite a remarkable result, I thought, and I was highly impressed with how much fidelity can be packed into such a relatively small amount of bitspace. If I was doing actual scoring, I would have awarded a 4.8 grade to the results I heard – the audible difference was that subtle.

The short clip chosen for us came from a DTS Blue Man Group recording, again using a spare, sparse selection for an easier and more revealing A/B comparison. Again, we found no differencebetween the uncompressed original track and the DTS-HD Master Audio version.

In addition to the DTS HD-Master Audio lossless codec, DTS also offers up a nearly lossless high bitrate format called DTS-HD High Resolution Audio, with up to four times the bitrate of their core DTS format, which we were able to audition via their Blu-ray demonstration disc. We then conducted A/B comparisons between the high resolution Blue Man Group PCM original soundtrack and the core DTS codec which has a Blu-ray and DVD bitrate of either 768 kbps or 1.5 Mb/s, in a somewhat similar but not totally blind fashion that we went through the week before.

It was déjà vu all over again. We switched back and forth between the original PCM master and the core DTS version, and here we found only the slightest, barely noticeable difference. From a frequency response standpoint, both versions were identical, with clearly delineated high frequency details, but the compressed version differed slightly only in barely noticeable presence —that sense of being “there”, with the original PCM track having just slightly greater overall richness. Whatever acoustic elements were removed in the code/decode process were clearly superfluous, at least for the most part, as the audible differences were so minor as to be almost unnoticeable—again, another testament to the capabilities of this highly refined codec.

So Subtle
What impressed, or perhaps surprised, me most about these tests was how good the base codecs actually are. The difference between the original audio and the basic Dolby Digital and DTS is a lot subtler than you’d expect, given the extreme amount of compression (around 10:1, a similar ratio to that of 128 kbps MP3).

That said, I could definitely pick out the difference between the lesser (or perhaps it’s more accurate to say “better”) compressed versions and the higher compressed versions. The difference is mostly in the presence, or ambience. The lossless, Dolby Digital Plus, and DTS-HD High Resolution compressed tracks were just a little more open and airy. I hate to say it, but they just sounded more realistic and transparent. The 448 kbps Dolby Digital and standard DTS tracks were less so, a little more closed off. Between the 640 kbps Dolby Digital and the uncompressed, the difference was even less noticeable. Enough so that most people, even those trained to listen for it, probably won’t be able to hear the difference.

The core DTS call is a little harder, as there wasn’t the same blind system in place to A/B as precisely as at Dolby. Results were similar, though.So by all means go for the new codecs, as they definitely sound better than what was on DVD. Uncompressed PCM, on the other hand, is just a waste of space (though compatible with everything).

If you’ve been listening at home and are sure you can hear a difference on your favorite discs, be wary. There is absolutely no way to tell that compressed and uncompressed tracks on any disc have anything to do with each other. They could come from different masters, they could be mixed differently, or any number of other variables that makes an in-home test, unfortunately, impossible. That said, trust your ears, and go with the one that sounds best to you. –Geoffrey Morrison

Was wondering if anyone here that hears a big difference between both. I don't actually hear a big difference, I still enjoy the sounds from DVD.... sometimes surprisingly better experience than watching blurays.

Recent dvd movie I watched was TROPIC THUNDER, the explosions and bullets were awesome, made me jumped (similar to SAVING PRIVATE RYAN last time).

I feel lossless sounds from bluray have slightly higher clarity and bigger space feel (like those amplifier sound fields/processing). But in terms of punch, seems less.

What you think?