Ajax, if it was me, I would forgo the meter and play a variety of source material and do it by ear.
I'm betting that you can set it up with an SPL with no problem and be accurate using pink noise but I would guess that you will find that the sub will call to much attention too itself on some material.
Play and bunch of stuff and adjust (On the sub) as you go. Eventually you will hit a good spot.
I say this only because almost every time I set-up my HT system with a SPL, it sounds great with movies, DVD-A, SACD, and even multi channel stereo but...............when I switch to stereo only with sub, the sub is overpowering on most material and that is with a cross over setting of 60. I truly believe that there is no right and wrong with stereo set-up. It comes down to what you like and the way you want it to sound.
