The standard format for lossless music (no loss of data, CD standard or better) is FLAC (free lossless audio codec). The FLAC format has become the standard because it allows lossless data to be stored economically. It stores a typical CD of music in half the space that the original CD data took with no loss of information (400 Megabytes versus 800 Megabytes). Most high-resolution download sites have music under five different quality levels (not all music is offered at all levels; most is still only offered at MP3 and CD quality): MP3 (avoidits compressed), FLAC at CD standard (very good), FLAC at 24-bit, 48 kHZ (better), FLAC at 24- bit, 96 kHz (best), FLAC at 24-bit, 192 kHz (hype and overkill). Most high resolution music made the jump from 16-bit to 24-bit (skipping 20-bit) because computers prefer numbers divisible by eight (seriously!). 24-bit encoding gets you more data than you need, but not by much.
I have downloaded two high-quality items in the past year: Soltis Rheingold at 48 kHz, 24-bit from HDtracks.com and Vanskas Min- nesota Sibelius 2nd and 5th symphonies from eClassical.com at 96 kHz, 24-bit. I had no trouble with the payment (credit card or PayPal) or download. With each download I was sent the liner notes in PDF form. I can verify that the data are of the resolution that they claim to be and they can be copied onto other devices. The download speed will vary, but I was able to download each in under 30 minutes. The files come in their own directories. The Rheingold, two discs, was 1.6 Gigabytes; and the Sibelius, one disc of better quality, was 1.3 Gigabytes. The sound on both is wonderful. Note that with a disc burner I could store three original CDs, at better than SACD quality, on one DVD (with the accompanying PDF liner notes). The highest digital quality Beethovens Ninth Symphony, perfectly faithful in human listening fidelity, to the master tapes it was recorded on and in seven-channel surround sound, would still fit on one DVD. I cannot envision a need for any better audio recording technology.