Many mastering studios don't really dive headfirst into formats of the audio you're about to have mastered. Many times they simply master your audio to a .WAV file and deliver. The reason is, and it's rather a consensus, one master should be good enough to cover all release market mediums you're going to choose. One master should be good enough for CD, Spotify, Tidal, YouTube, Apple Music, and sometimes even vinyl.
Not to ruffle a few feathers but I find that to be rubbish, myself---sort of. Keep reading. I still believe there is no "one size fits all" format for your music. This isn't totally an objective music mecca we're dealing with. Listeners have expectations, and so do artists, labels, producers, etc. It's not that one master couldn't suffice for all release outlets. It's that the owners of the music aren't always agreeing on what gets the paycheck. One could argue that they've mastered many, many artists and not one has requested their CD be louder than the conservative -12 LUFS master that was delivered for streaming platforms. I don't commonly hear artists complaining about a CD not being loud enough, either (quite the opposite, at times). But they don't all want a quiet CD.
The trouble comes in when an artist later hears the music on a radio show, vinyl, CD, or other platform right after a hugely successful artist, and the lack of volume or assertiveness is quite deflating. Yes, I agree the listener could just turn the volume up higher. I miss the days of masters that just sounded great, regardless of volume, and I'm happy we're hunting for that again. Case in point: The Level42 Running In The Family cassette I still have from its purchase in 1986 was mastered low, very low in volume. It was weak. It wasn't impressive. But it was clean. If you cranked up the volume, it sounded like a great mix! Still, a lot was left to be desired. Why was it so quiet? As soon as I replaced the cassette in my player with a modern pop artist cassette, right then, I knew the Level42 cassette wasn't fun to listen to. It didn't energize me. In fact, I realized the noise floor was apparent in the Level42 album. You could hear a bit of tape hiss, although, with Dolby noise reduction enabled, it was good.
Boy, am I dating myself here. So, what I found was, in my ignorance as a kid growing up then, even though I personally miss the cleaner masters of the 80's--especially New Wave, I realize that the audience doesn't always share that appreciation. Listeners want energy and power! They want to hear the music on a loud train through ear-buds. They want to be energized and moved by the music, not simply sit silent and appreciate it.
This is the main reason why I believe every master that's going to CD, vinyl, cassette, radio airplay, streaming, or MP3 be a different format with its own set of criteria for success. It's not a simple Save to a new file. There's a great deal more to be cognizant of, such as inter-sample peaks, bottom end (for vinyl), tape hiss and "head-bounce" for cassette, CD commercial competitive loudness, and quality deprecation for streaming platforms. Providing the same file for all of these is rather a shame, I think. While the file may be the best quality master for the song it may not be the best surviving quality for the release medium or platform.
"Aim for the best quality of the song. Don't worry about whether it's for CD, streaming, etc. Ask for the best master of the song and it will be fine."
Yes, it will be fine. But fine isn't where I finish. I want to give your music more than simply just a clean, transferable master. I don't want to compromise your music to best each medium or platform but if there's a measurable and audible quality improvement for each medium or platform not taken advantage of for a song's success that's like leaving money on the table. If your music could be audibly louder on a CD, when there's no significant change in audio quality, wouldn't you like to take advantage of that?
More, if you have an awesome sounding CD master but the guitars have tons of low-end, left and right, this might not quite suit vinyl very well. You could end up with a vinyl record that skips or just sounds distorted.
It's not cost effective for a mastering engineer to master your music for different platforms
Ehh, maybe not. For some engineers, they charge a suitable fee for covering all platforms. Others might deliver your music on all of them, which is handy because then you can later decide where your music is released. Some find that performing critical listening on each file is time-consuming and not profitable. I can relate to all of these attributes.
So, how can I offer different formats at a low cost?
It's not really a secret, and my process allows me to make a single master that will perform well for ALL mediums and platforms with only slight modifications. I load the music into a "pitcher" DAW. If there's multiple songs I will load them all into the same session and work on them in some uniform state so that I can bring them all to the same cohesive context of the album or collection. Once I've corrected problems and completed the individual song pre-mastering I will stage them all to go through the analog mastering chain.
I will play each song through the analog chain to a "catcher" DAW and save the resulting files as catcher files. From here I will develop a digital final mastering chain that will produce the best master for each platform. This gives us everything we'd want in a master that best suits the song, NOT the format (medium or platform). Next I will work on what needs to be addressed to provide the best delivered master for each medium or platform. I don't need to run the music through the analog chain again for each format. (I also never clip the audio in the ADC (Analog to Digital Converter), in case it's a question in your mind--I'm rather conservative here on level).
If you want a loud CD, the final mastering stage is where I make it loud. If you want vinyl, this is where I tighten up the bottom end to best suit vinyl. If you want streaming, this is where I will work with many different codecs and streaming platform compliance to meet the criteria, meanwhile maintaining a great master. I don't have to perform an entirely new master for each format.
This lowers my cost, but I always perform a critical listen of the resulting audio through my audiophile headphones and headphone amp before delivery to ensure a clean master. There's just a minor additional cost for each format. My pricing allows you to pay only for what you're getting. If you don't need CD's then don't pay for that. If you don't need vinyl then don't pay for that. Pay less and only add formats as you need them. Everything I do is "recallable" (within reason). I never need to worry about any analog gear changing (aging or being sold/bought) down the road. Your masters have already passed the analog chain and are safely stored where they can be recalled. The final mastering chain is saved safely and, unless a final-stage plugin is no longer supported or, I can't recreate the character in another, I can work from the very same mastering chain, indefinitely!
"One size never fits all" (RFC1925 - Rule #10, for you I.T. professionals). One master might rule them all but when you're exporting files for different platforms or mediums, if you're not paying attention to the benefits and drawbacks of each one, you might end up with "less for best" quality. Yes, one mastered file might suit all platforms well but it can be beaten by a master best suited for the medium/platform where the audio reaches the listener.