24 Bit WAV or AIF.
Multiple Mono (Recommended) or Stereo Interleaved.
NO Buss Compression.
3db Headroom (audio should peak no higher than -3db).
If you are recapturing your final mix from an analogue source or have yet to commit to a sample rate we recommend working at 96kHz.
If you have already committed to a sample rate as you are mixing within your DAW please provide audio at the existing sample rate to avoid any unnecessary sample rate conversion.
To send these specifications to your engineer please use the link: https://bluepromastering.com/faq/prepare-audio-mastering/