I currently use the Komplete Audio 6 interface, with an AKG-Perception 220 hooked up to it.

The vocal quality I'm getting right now is decent, but for a budget of $500, which piece should I upgrade more to get a better quality?

$500 CAD by the way, but I can most likely match $500 in foreign currencies (as long as it's not GBP, hehe).

Please be detailed, I picked up this setup approximately 2 years ago on an ignorant mind, now I'm just interested in picking up the highest possible quality for my songs.

P.S: I understand much of the work behind a great sounding song is done by engineers, but I want to make sure I'm getting the best audio stems I possibly can.

TL;DR, Komplete Audio 6 & AKG-Perception 220 at the moment for Rap/R&B (PartyNextDoor etc.) type vocals, have $500-600 budget to upgrade one or both, post suggestions below that would mostly maximize improvement.

Salute!