...at 16 bits with a 44.1k sampling rate and no compression. Producing the correct frequency and precisely reproducing a sound are two very different concepts. If covering the whole range of human hearing was the only requirement, then all digital audio files would be mono at 48kbps.
For most equipment and most recorded music, you can't tell the difference between CD and any higher bitrate source. There's the problem of everything from microphone to recording studio to encoding to distribution format all the way to the end user's speaker must be of high enough quality that there is a difference. HD CD's and Blu Ray audio never took off because the market of consumers willing to spend $$$$ on that sort of equipment is tiny. It's about 10000% more convenient to buy it on iTunes and it sounds really good over a pair of $$$ headphones.