Any good way to use the headphone outputs as if line level?

[table17]

Hi all. I am considering installing a summing mixer. I'd use the D-sub line outs (line outputs 1 - 8 on back of Carbon). If I wanted to also patch audio as routed to the 4 headphone jacks into remaining summing mixer channels, any tips on getting that to work correctly?

What I mean is, I'd have the four stereo headphone outputs on the front of Carbon separated to 8 mono signals, then into the summing mixer channels 9-16 as unbalanced audio. Is it as simple as gain staging to match level (say, with a signal generator)?

I guess one issue is that the headphone outputs would be unbalanced, so I'd need to check specs on summing mixers for acceptability of unbalanced inputs.

So far, my other options are: re-install of my Apollo 16 Mk2, but that's not ideal because I want to keep Carbon as the only master audio interface if I can. The other option is using the ADAT outputs to send signal to stand alone DA converter(s) which would then feed the summing mixer.

Thanks for any tips or thoughts you might have!

[JFreak]

Yes, if you get the levels right. Just bear in mind quality is probably not what you may expect...

[dominicperry]

The S/N ratio will be different, the line levels will be different and the output impedances will be different. But it still might work ok, with some fiddling.

RME design (some of) their headphone outputs to be used this way, so it is possible. I think RME use very low output impedances along with high quality DACs and powerful output line drivers. So it depends on how Avid have made the headphone outputs really.