I think the the word "DVD Audio" got a little confusing.
My intention was to compare DTS found on a DVD Disc vs DTS Core and DTS HD MA found on a Bluray Disc.
1. So far the replies seem to say that the 1.5 mbps DTS Core of the Bluray Disc is "Superior by a Big Margin" to the 740 kpbs DTS of the Regular DVD
2. But how much Superior is the DTS HD MA vs DTS Core ( Both found on a Bluray Disc )
Answers to No. 2 is important for me to figure out as i'm planning to get a Bluray player. I'm quite happy with the sound of my current AVR Yamaha RX V450.
I believe the RX V450 can transfer and decode the DTS CORE 1.5 Mbps from a Bluray Disc via optical cable.
So if DTS HD MA is better than DTS Core by a "Huge/Significant" margin then i'll buy a new modern AVR capable of decoding the DTS HD MA.
However if the difference between DTS HD MA and DTS Core is not much than i'll continue with my existing AVR.
That's my dilemma.....
If your AVR can decode DTS, then it should handle the DTS core audio track from a BluRay disc's DTS HD MA track.
Now coming to your original query, here is my take on the situation.
Unless you have a very high end HT setup with a properly treated room, you will not notice any significant lack in audio quality when playing the DTS core audio track and the DTS HD MA tracks.
But all BluRay discs do not come with DTS HD MA tracks. Many come with DD & Dolby True HD. And this makes the comparision a bit less clear cut.
Here are the various audio formats under discussion in ascending level of quality as per my past experience with them
1. 384/448kbps Standard AC3 (Dolby Digital) on regular DVDs
2. 640kbps AC3 found on a few DVDs and BluRay Discs
3. 768kbps DTS on DVDs - Some would place a 640kbps AC3 stream at the same quality level as the 768kbps DTS streams found on DVDs, but I find audible differences, so I put the DTS tracks higher.
4. 1.5mbps DTS Core on BluRay discs with DTS or DTS HD MA
5. Dolby True HD or DTS HD MA - These in theory have the same quality as both are lossless audio formats
In general there is a big quality difference between the standard AC3 track and 640kbps AC3 or 768kbps DTS tracks. I suppose you already know about the differences between these various formats based on your past experience with DVDs.
Now the difference between 768kbps DTS and 1.5mbps DTS core on BluRay discs also exist, but not as dramatic as the difference between the base AC3 and higher bitrate AC3/low bitrate DTS tracks. But then again, this difference can easily be heard on any half decent HT setup using properly selected audio tracks and critical listening.
The difference between the 1.5mbps DTS and lossless HD audio codecs is even lesser and if you ask me, it should require a reasonably high end system to be clearly apparent. To me the slight difference between these 2 formats is so low that I would not bother much when watching movies. The DTS 1.5mbps tracks are extremely good with most movies.
The other advantage of the newer HD audio codecs is the ability to carry 7.1 surround sound. But even today most movies are mastered with 5.1 audio and while the standard has been around for some time, there are very few movies available on BluRay with more than 5.1 audio tracks. So this difference is not really a major difference.
Now the next thing to consider when playing back BluRay discs is that the discs typically contain either DTS tracks or Dolby tracks.
Those discs which contain only Dolby tracks. i.e. Dolby Digital and Dolby True HD, will show a very significant audio difference between the high bitrate Dolby AC3 track and the Dolby True HD audio track. But then to me the difference is nowhere near the quality difference I see between the video on a BluRay disc and on a well mastered DVD. The audio differences
Those discs which come with DTS HD MA will output a 1.5mbps DTS track to your existing AVR. On these discs the difference is quite small. I would say that you will need a really good quality HT setup to observe the difference.
What I would suggest to you would be to find a HT dealer willing to demo you these differences with a few selected BluRay discs on a high end HT setup. Do not just test using the audio track selection feature on the bluray discs to flip between HD & non HD audio but for running non HD audio hook up a coax or optical cable to the AVR from the BluRay player to know how a bluray player will really behave in your kind of a setup. This would be the best way for you to see the actual difference when applied to a high end HT setup. Next do the same demo with what you plan to actually buy and see if the differences still remain relavent in your case.
Overall I would say that using an older generation AVR which is capable of only playing back DVD audio formats will not take away the movie watching experience of BluRay discs. Now if you are just looking for a reason to get your wife's approval for a new AVR, then this should be good enough
Another thing to consider is that if you are looking for an audio quality upgrade of your HT setup then you will most likely get better results by doing some basic room treatment if you do not have any or with a speaker upgrade than just an upgrade to get HD audio with your existing speakers and room.
-- no1lives4ever