confused on audio file formats

Go with a lossless format - FLAC, Apple Lossless, etc. FLAC is the most universal one and is supported by more hardware and software.

-RW-

Agreed about FLAC...unless you want to use iTunes to organize your music. If so, it will not handle FLAC files. If you are using iTunes I'd suggest AIFF. 24/192 represents a sampling rate and not a file format. In this case it represents a very high sampling rate that not many DAC's can handle, and not much music is available in. Music from a redbook CD is 16/44. The high-rez music services like HD Tracks are offering music sampled at 24/96 which most of the modern DACs can handle, and depending on your system and your discrimination you may be able to hear differences from the same material from a CD at a lower rate.

Here's a thought provoking passage from the wiki on SACDs:

In the audiophile community, the sound from the SACD format is thought to be significantly better compared to older format Red Book CD recordings.[35] However, In September 2007, the Audio Engineering Society published the results of a year-long trial in which a range of subjects including professional recording engineers were asked to discern the difference between SACD and compact disc audio (44.1 kHz/16 bit) under double blind test conditions. Out of 554 trials, there were 276 correct answers, a 49.8% success rate corresponding almost exactly to the 50% that would have been expected by chance guessing alone.[36] The authors suggested that different mixes for the two formats might be causing perceived differences, and commented:

Now, it is very difficult to use negative results to prove the inaudibility of any given phenomenon or process. There is always the remote possibility that a different system or more finely attuned pair of ears would reveal a difference. But we have gathered enough data, using sufficiently varied and capable systems and listeners, to state that the burden of proof has now shifted. Further claims that careful 16/44.1 encoding audibly degrades high resolution signals must be supported by properly controlled double-blind tests.[37][38]

This conclusion is contentious among a large segment of audio engineers who work with high resolution material and many within the audiophile community.[39] Some have questioned the basic methodology and the equipment used in the AES study.[40]

Double-blind listening tests in 2004 between DSD and 24-bit, 176.4 kHz PCM recordings reported that among test subjects no significant differences could be heard. However, the youngest participant in this test was 22 years old.[41] DSD advocates and equipment manufacturers continue to assert an improvement in sound quality above PCM 24-bit 176.4 kHz.[42] Despite both formats' extended frequency responses, it has been shown people cannot distinguish audio with information above 21 kHz from audio without such high-frequency content.[43]

Of course who knows what these folks were listening on and what kind of controls the experiments had. Best thing you can do is just get a few different files and listen for yourself and see whether it makes a difference to you.

Just use AIFF which is a Mac native uncompressed file. FLAC and ALAC (Apple lossless aufio codec) are both compression schemes. Hard drives are cheap. The only thing that might be better than AIFF is WAV. WAV does not support file tagging in a way that is acceptable to most people, even though it is documented by many to sound the better. If you so choose, you can convert from one to another. Nobody seems to really understand why (if at all) one could be different than another as they end up being the same bits. Ultimately the best thing to do is rip a few well recorded cuts and in the formats that interest you and see if you can discern a diff. I was amazed/chagrined. Later you can batch convert. What ever seems to be going on, it appears to be in "real time" playing, not the ripping. Once you get the rip correct conversions are easy, albeit painful to us OCD audiophiles.

The bit about SACD is really moot. One cannot directly compare as the SACD files are not compatible with most DACs.