Actually, a cable is a cable. You could run a soundboard output on any cable, but it sure is not the optimal solution. Coaxial is not optimal for running sound, but you could do it. You could use a network cable if you wanted to (CAT5), a power cable or whatever. Cables are optimized for different uses and coaxial cables are not optimum for sound.
Optimal if you want a long cable is instead to run a shielded two-pair cable. Exactly same type as microphone cable. On the mixer side, get a converter so you could plug into either XLR or TRS, mixer boards generally comes with either of these.
On your recording side, the optimal solution is to have a transformer before going into your box. These are sold under name of "passive DI-box" or similar and are typical problem solvers used on the stage and in the studio. Not having one of these, run the balanced input to your box. If your box has only unbalanced input, you might be able to connect to ground/hot (pin 1 and 2 in an XLR) but this depends on the configuration of the mixer output. This will work with most, but not if the mixer has a transformer output. Then ideally you should run pin 2 and 3 (hot and cold) into your unbalanced input. Here is where the DI box again is a true problem solver.
Regardless, good luck.
// Gunnar