Just make sure you’re using a balanced connection. Best place for 99% shielded line cable or quad is redco.com
Cheaper to get 20’ of mogami dual shielded with custom connectors and length than it is to get a premade cable of the same length and not dual shielded. It also doesn’t hurt to go quad cable.
Scarlett is fine, focusrite is fine; I like MOTU and RME. M-Audio I have had trouble with, but the hardware itself isn’t bad. if you’re balls to the wall, get a sound devices mixpre 3 or 6.
JBL makes some quality speakers, I have put several hundred hours on others in the LSR line.
What I prefer is the yamaha hs7, as the mids are crystal clear. KRK overdoes the bass more often than not, and JBL’s are not terribly different.
Maybe try the hs5 for that price bracket. They lack a little in bass, but not much. Look around, call guitar center and ask for a deal (they are on commission sales), or check the used market.
“Dolby atmos” is its own thing. It’s a theater-only system with a home version for decoding those special files. You probably won’t be doing any atmos decoding on a PC. Maybe if you have a receiver, but that’s kind of going the long way around. I worked that way for a few years (PC out optical to receiver, out analog line to interface, out to speakers through interface embedded DSP) to check if Dolby encodes were working and to play games, but it’s mostly a waste of power and space. Dunno if that’s exactly what you mean by atmos, but seriously my suggestion is don’t worry about it.