dd/dts hddd/hddts

[hal]

hi all just joined the forum, does anyone know if theres much difference between dolby digital , dts and the hd versions as ive not heard anything in the hd versions yet and wondered if it was worth upgrading my denon avr-3801 or not if theres not a huge difference in the sound. also have a yamaha dsp a970 id like to get rid of anyone any idea what it worth its like new been boxed up since i got the denon almost 8 years ago.

[PMM]

DTS is better than DD

Not heard any HD-DTS / DD so cannot comment its men't to be lossless compression compared to std DTS/DD so the HD version of each should be equally as good and in theory better sounding but as mentioned I have not had the luxury of having heard HD format..