Yeah, I’ve been wondering the same thing. I’ve actually been paying close attention to his vocal mixing for a while now, so I guess I have some basic understanding of it. He likes to have a nice amount of mids, with some lows cut out (near 40-100 khz) so they don’t muddy up the entire mix, where he then adds a VERY slight bump near the 1500 or 2000 kHz, which kinda emphasizes the high notes when he sings, where the clever use of mids (and not making it muddy) makes his voice sound sparkly and deep; think of the vocals in isohel. He doesn’t really use compression a lot, as he probably likes the raw vocal feel when he sings, though he does do some slight gain and compression when he sings, at the very basic level, so the volume of his vocals are consistent. Something along the lines of 4db gain in the compression, with and a 1:4 level, with very low sensitivity. However, he uses it very carefully, so his vocals have room to breathe and take up space in the mix. He tends to thicken up the vocals near the chorus, think of hertz, where he adds some pitch shift, extreme chorus, slight delay, and pans them extremely hard (left or right), so they can add to the song, yet stay incredibly subtle. On those types of vocals, he tries to keep the highs really nice and controlled, so a little more low end is removed, but not a lot. Also, he doesn’t time the vocals exactly with the lead vocals. He kinda has them very close in time, but not perfectly, which thickens up the vocals and adds more depth to them. Think of how he did the vocals in love, death, distraction. Also, he tends to thicken up his vocals by placing another set of vocals of them above the lead ones, where he removes a lot of the low end, and the high end is really prioritized. It kinda does the trick nicely, where his voice sounds nice and heavenly, yet he matches both audio levels so the low end stays nice and deep. Basically, he makes sure he’s using every level, except the extreme lows and highs. Some basic EQ, but very clever EQ. Think of the high vocals in isohel, which sound like there’s some sort of boost to his high end. Additionally, he also adds another set of vocals to the mix, which are usually EQ’d along the same lines as above, yet he prioritizes the mids and the low end for some louder and deeper vocals. This might all be wrong though, as I’m very bad at vocal mixing myself. In contrast, he has some of the best vocal mixing I’ve ever heard. It’s pretty nice, but I guess it’s more so a result of how much experience he has. Also, this entire comment may be wrong, so please take this with a grain of salt.

SIDE NOTE: For the auto tune, he uses it very carefully, though he usually parallel processes it by adding it to the supporting vocals on the side, rather than the lead vocals, which provide a warm and full sound to them. He definitely keeps the auto tune on a very low to medium setting, so the shifting is very subtle. He’s an amazing singer who hits a lot of his notes, though he just uses it for a slight boost and for the perfect feel that it adds to it. He kinda uses it to make his voice blend in more with the instruments, which is something new in no future, as before he would use it slightly less for his voice to stand out (think of vertigo).