generaly, but as long as you know what you're doing there shouldn't be a problem to send all the signal thru a "pre fader" (software) aux send
and pick up the relevant signal as your new channel.
(this is of course procesing from tape and not a pre A/D compression,
which should be done preamp->comp->A/D.)

obviously, if we knew what recording chain we're talking about things would be more concrete...

a