Ronnie Jones - Why Don't You Stay

[filipandrei]

What I've learned over the years is that smooth or silky voice comes first from a clear voice, and adding a bit of "air" EQ (8K - 12K area).
Also learned that a clear voice is around 1K-4K area, where our ears are most sensitive to (that's how they work, right?).
So, my suggestion, and what I usually do, try keeping it clean in this range, and make space for it (maybe EQ other instruments / tracks in the song), then apply a bit of 8K-12K boost

I've never used RX for mixing a song, thought it is specific for some other audio tasks

Cheers