If you use DX7Pro with Atom:Looking to output rca in the Atom. But the measurements are xlr, so I'm curious of the rca.
DX7 in DAC mode -> connect to Atom thru RCA at the back -> then you can use headphone out or rca outs on Atom and use Atom volume knot for volume control, up to you.
RCA measurements doesnt really matter I think. You would probably stack them and run a very short pair of rca cable anyway