This article includes some recommendations. These recommendations come mainly as a result of controlled blind listening tests over a number of years and with a number of groups of audiophiles, and also from several years of full-time experience. This is not the place to present theories to support these recommendations, because of how many words would be required. Here are our recommendations.
We recommend you use an uncompressed file format. In listening tests, uncompressed FLAC sounds considerably better than compressed FLAC. We appreciate that many learned people deduce that there can be no difference because the data is the same. This deduction is unsound and a reach, as the task is not about moving data from one place to another, but is about generating a clean digital audio signal, and the challenges that presents go beyond the simple mental model that people often argue from in this field.
We also recommend Uncompressed FLAC over AIFF. The sound differences are minor but the AIFF standard can create compatibility problems for you at some stage.
WAV files will sound different from Uncompressed FLAC, but in blind tests the preferences are split between them. The WAV file usually flows a bit easier, and the Uncompressed FLAC file sounds a little tighter. We recommend Uncompressed FLAC over WAV because it degrades more gracefully. All file storage degrades over time. This is simply not an issue with the majority of file formats, but with a raw file format such as WAV, the result can be irreversible, audible ticks, pops and even stops. Damage to a FLAC file is also irreversible but is generally inaudible. This is because the FLAC file resilience identifies errors and masks them in a way that a WAV file cannot.
We recommend you minimise the number of times your files are converted to a different format. Even with reputable software, that claims to convert files using a bit-perfect process, it can easily be shown to degrade the sound with each conversion.
For these reasons, Antipodes servers rip to Uncompressed FLAC. But Antipodes servers will play any format that does not have “protection” on it (rare to see these days).