There are some good meters out there that can help with this before you burn the CD. Just sayin'

May be all he needs is the knowledge of how to insert a decent meter or two on the main output of the mixing software. VST or otherwise.

Final decision is made while actually playing it through the intended system as mentioned previously (of course), but you should be able to get them reliably close..

I do not work here, but the benefits are still awesome
Make your sound your own!