Hey, I'm no expert, but this seems a slightly risky approach to me.
*for the purposes of this reply*, we are presumably working on the assumption that 'burn in' physically changes the sound signature.
I haven't heard of it increasing volume. That's not to say that it won't, but I've personally never heard of that. Other more experienced people can chime in if they have.
We don't know what the issue with your Hunter is. It could be a connector pin or cable issue, or even something to do with the termination or even your DAP's connector socket/hardware.
If it turns out to be anything *other* than an IEM issue, then you may have yourself an assymetrical sounding set of IEM's afterwards.
Personally, I'd burn both sides in equally and see what happens.
Of course, if burn in really has no real effect, then none of this will matter