Apple has never talked about audio specs, not frequency response, not signal to noise ratio and certainly not jitter. This was obscure stuff best left to the audiophile population to try and decipher for themselves.
Apple is largely feature-driven, which is what most of their audience is also interested in. They may talk about performance when talking about faster multiple core processors or higher resolution retina displays, but the only audio performance enhancement they really ever talked about was the move to replace a large portion of their iTunes 128kbps songs with 256kbps non-DRM songs.
I always thought Apple had some of the best designed hardware, but I was actually somewhat surprised to find out by comparison how frequency-limited the Apple ear buds were. They were inexpensive obviously, but when I compared them to a half dozen other inexpensive ear buds and headphones that I had laying around, I realized that for whatever reason they were the worst sounding of the bunch. Go figure.
I would expect to hear some talk and possible comparisons of the new Airport Express on the Computer Audiophile site.
Steve