I have another question that I used to know the answer to but I've been
away from audio stuff for quite a while. I have an audio device with an
unbalanced RCA output connected to a Gentner AP800 mixer designed for
conference room applications. It is connected to a line input. I'm
trying to convert this to a balanced connection. Do I just need a
matching transformer?

I'm trying this right now and the levels seem to be quite a bit off,
more than I would have expected. I'm coming out of the audio device via
RCA, then going to an inline matching transformer. I then have an XLR
mic cable running to the mixer. The connector on the mixer is a phoenix
plug.

Is this just going to cause level differences that need to be corrected
by tweaking my gain settings, or is there more that I really should be
doing to make this work right?

Thanks!
John