I did some A/B tests with the 96/24 version of Ron Carter / Rosa Passos 'Entre Amigos' vs the 44/16 bit version. My subject was a pro jazz musician. Playback was with Audio-GD NFB-10ES as the DAC and headphone amp, headphones were LCD-2 and HD-800. Also used was a Soderburg modified Forte 4a and a pair of Quad ESL-57's refurbed by Wayne Piquet. We also used a pair of Mackie powered monitors that the musician was well familiar with at times. (I didn't like these speakers but he was very familiar with their sound, having used them in pro recording sessions, movie soundtrack creation and so on.)
We also used SACD and Red Book tracks from several hybrid SACDs using a well-regarded Sony SACD player (model number escapes me right now.)
Neither my pro musician pal nor I could hear a difference. We listened very carefully, for quite a while.
I'm not saying that there is NO audible difference. I'm saying WE couldn't hear any difference. I suspect that if there were MAJOR SONIC BENEFITS from these hi-res tracks, we should have easily heard them. Since we listened very carefully to quite a number of things, my conclusion is that if there really were clearly audible sonic benefits we would have heard them, and since we heard no such thing, I suspect there are no clear sonic benefits from these high-res formats. Maybe some really subtle benefits are present, and they escaped our attention- but if the benefits are so subtle that a pro musician and a trained 'audiophile' listener couldn't hear them, then I conclude that any such benefits are not worth all the trouble and expense of obtaining these high-res tracks. Your mileage may vary- and you are entitled to your own opinion, even though it's wrong
That said, there certainly IS a benefit to be had in the studio when recording music- various studio manipulations and other elements of digital production yield much better sounding results when you start with higher resolution tracks to begin with, even though in the end it's mastered to 44/16.. It's just like editing a digital photo- the results of your cropping and photoshopping the image will be much better if you start with a 12 megapixel image shot on a prosumer D-SLR than if you began with a 4 megapixel image from a cellphone.
As to Red Book CDs being 'compressed' as some have claimed- well, there is something over 100 dB dynamic range available from a 44/16 CD. I doubt there is a symphony hall anywhere in the world where the range between background noise and maximum orchestral crescendo is more than 75 dB. A rock concert is usually between 80 dB in the quiet parts and 125 dB at it's loudest, a range of 45 dB! A really good vinyl playback system struggles to reach 70 dB. So, the 100 dB dynamic range of 16 bit CDs is not compressed in any meaningful sense. Now, what the music producers do to the signal is another matter- we all know that many CDs, even classical ones, are made LOUD, which is to say, compressed. But this is NOT a problem with the format. Maybe in producing 96/24 tracks from original masters, the producers don't feel the pressure to win a loudness war, so in that sense high-rez tracks may have less tampering with the dynamics than the commercial CD release. But again, this is NOT a problem with the 44/16 format, but a problem with industry practice.
It's also interesting to note that there is an (in)famous Audio Engineering Society white paper from a few years back which presents listening results from a large sample double-blind study of 44/16 and 96/24, and this study showed that none of the listeners tested could hear the difference. (Actually, there are a few papers on this topic- see: https://secure.aes.org/forum/pubs/journal/?ID=2 and http://www.aes.org/e-lib/browse.cfm?elib=3839 and also see material from these studies quoted in the Wikipedia article see http://en.wikipedia.org/wiki/Super_Audio_CD#Audible_differences_compared_to_PCM.2FCD )