What
exactly are your backing tracks - that they have to be recorded
at the same time as your vocals are being recorded?
The reason I'm asking is that
the standard way of working (although not the
only way)
is to record your backing track(s) say Track 2
then
record your vocal (Track1)
while listening through headphones to Track 2.
That's why I'm asking what,exactly,is "stereo mix" on Track2.
If it's a cd or samples or a synth or
anything that can be recorded,then you'd normally record that first onto Track2.
If "stereo mix (Track2)" is something that absolutely can't be recorded on it's own,then that's a different problem.