So you get a snake that’s 25pin DSUB to 8 TRS connectors, and then you’d get TRS to RCA adapters. I don’t know if you can get 25pin DSUB to 8 channels of RCA. You can always make your own, you’d just need the pinout for the DSUB and chances are it follows the Tascam standard.
Yeah...I don't think I ever saw a DSUB with RCA connectors.
Also...with the RCA, you're dealing with -10 reference level, while the interface is pushing out +4.
Not sure if that can be changed in the interface...but if not, you also need to account for that...and the fact that you are unbalancing the XLR wiring going to RCA.
A simple way to solve all that is use something like the Fostex 5030 line amps...which had just the right connections and power conversions for what you need...all in one box.This is what I'm talking about:
Fostex Fostex 5030 Line Amplifier | Reverb
Trouble is...they haven't been made in a looooong time, and don't come up too often on eBay or Reverb.
I have a pair of them in my studio, from when I had more RCA/-10 connections to deal with...but over the last several years, I've weeded out almost all of that gear. I think the only thing I have left is one consumer level CD player and also a cassette deck...oh, and my old tape echo machine, which uses unbalanced 1/4", but at least it has some options for I/O levels.
I was actually thinking just the other day why I still have a pair of the 5030 line amps in my rack...
...since I rarely use even the one unit, but it's one of those things you never need until you don't have it...
...plus they are both still wired into my patchbays, and I'm too lazy to pull all that out. I would have de-solder the PB connections.
Anyway...there are some other line amp boxes out there. Tascam made some way back, though also rare...Ebtech still makes some, though they don't make them for RCA connectors:
Ebtech - Audio Solutions