File types:
confusion and resolution


File types: AIF & WAV are full quality PCM files supported by almost every major DAW. Both are capable of encoding at 32 Float, and 24/16 and even 8 bit fixed point sample depths and at any sample rate.

When transferring files for continued work, please stay in these formats at the highest bit depth and sample rate you are working in. If you need to limit the file size to send online, use a Zip data compression program, as this is lossless.

If you convert to a lossy format such as MP3, AAC, or OGG, the quality is stuck at the compression rate of that codec choice* forever onward. 

It is important to remember: Converting back to PCM files after a lossy conversion gains nothing. Once those file types throw the data away, there’s no getting it back.

Sample rate:

This is the Bandwidth of frequencies that can be encoded in your DAW Session, also known as Samples Per Second.
If you are working at a particular sample rate, for example 44.1kHz or 48kHz, some people assume up-sampling to 96kHz or more is a good idea.
Doing so doesn’t gain anything if the entire mix was crafted at 44.1kHz, at least until the mastering stage.
If you are working at a higher sample rate when tracking and mixing, by all means, stay up there!
Mastering engineers love getting native high-resolution files.
Bit depth:

This is what gives you the possible Dynamic Range of your digital encoding system.
Making 24-bit or 32-bit WAV or AIF files is the best way to ensure a good mastering process.
If you go down to 16-bit, you will lose some resolution unnecessarily. If you require 16-bit files for printing CD’s, for example, that should be the last thing in the mastering process.
Mastering engineers can prep the files with dither and headroom so that no clipping will occur on certain CD players. Conversions to the lossy codecs are maximized in the mastering final stage as well.
For stem mastering it is best to set up group busses using auxiliary tracks in your DAW, and then run them all down as separate stereo group WAV or AIF files for your mastering engineer. This is something I do often, so please reach out if you have any questions.