Everyone I talk with from artists, bands, producers and engineers has this to say about mastering: it's the most mysterious part of the process.
I started off as a musician playing around town, then a producer, then a mixer. I would be at the end of an album, frustrated and making tweaks endlessly, never achieving the final sound I was looking for. How many times have we been there, right? Almost twenty years later, I've learned a lot about the art of finishing mixes, and that's where mastering comes into play.
Mastering is simply preparing your music for a release format. The most popular formats these days are mp3's, mp4's, spotify streaming (yes they all sound different than off your computer), CD's, vinyl, video, television, Youtube, and so on.
Each format release has its own quirks, and making sure that what you're hearing now will be what your audience will hear can be an art in itself sometimes. There's tradeoffs, and when possible we'll make specific masters for each format.
Archived music can benefit from remastering, since the equipment/techniques/acoustics have become much better in the last ten years.
You could write books and books about mix processing, and a lot of times those effects you have on the mix bus aren't actually helping you get the sound you're looking for.
Most mixing rooms, speakers and headphones aren't perfect, and acoustics plays a huge role in ensuring you're really hearing what you're hearing. Most people do great work but are missing out on big chunks of the frequency spectrum.
Online mastering algorithms aren't intuitive enough to know the difference between a technical problem and an awesome musical quirk, and simply can't be by their nature. At best they make things louder and different.
Working with you to get the best mix prints you can, then tweaking in an awesome room with accurate monitoring guarantees you the best playback you can get on the most speaker systems out there.
Best thing to do is to say hi and send a mix, we can see what your monitoring and acoustics are like, and get you the best sound you've ever had. That's my job, and that's mastering.
I did a quick look through archives and the artist directory, and here's some people that I've worked with over the years:
Paquin Entertainment, K-Tel International, Private Ear Recording, Bigshig Music, Signpost Music, Shawn Dealey, DB Benedictson, CBG Artist Development, Lemon fresh Sound & Music, Dacapo Productions, Stereobus Recording, Barbara Joy, Bubba B, Cassidy Mann, Don Amero, Jaylene Johnson, Karen Hammarstrand, Keith Price, Kelly Bado, Linda Koley, Mal Magorel, Quinton Blair, Raine Hamilton, T. Nautilus, Steve Bell, Steve Kirby, A La Mode, Collage A Trois, Dirty Catfish Brass Band, Quincy Davis, Duotang, Oh My Darling, Red Moon Road, Richard Gillis, Seanster and the Monsters, Sweet Alibi, The New Lightweights, Those Guys, Janice Finlay, Trio Bembe, Amber Epp, Erin Propp, Larry Roy, MJ Dandeneau, Aaron Burnett, Alpha Toshineza, Anda, Daniel Roa, Dave Quanbury, Del Barber, Elessar Thiessen, Gentil Mis, J. Riley Hill, Jocelyne Baribeau, Katrina Van Humbeck, Madame Diva, Mamadou, Marijo, Matt Epp, Mitchell Schimnowski, Rayannah, Sol James, Tansy, Tyler Del Pino, Vanessa Kuzina, Warren Friesen, Roman Clarke, Liam Duncan etc...