The idea of calibrating your home theater to a reference standard is appealing.
I did it a very long time ago with a rather expensive Preamp/Processor and an SPL meter. Once I was done, I was told that setting the volume control on the preamp to 0dB would then make the movie have the volume level, at my chair, that the director intended.
What I got was wildly inconsistent. On some content 0dB was loud, but tolerable. On others it was so loud that I never made it to 0dB. I stopped at -9 or so where it was already uncomfortably loud.
Perhaps more modern transfers to BluRay have more consistent volume levels with regard to reference level. But I suspect they really don't.
In my opinion, getting your speakers positioned correctly, then getting the crossover values for each speaker, and the relative levels set correctly, is far more important than reference level calibration.
...and as long as we are on the subject, I'll tell you what I think is the greatest untold secret in modern home theater: Uncompressed (non-lossy) audio on BluRay. PCM of course falls into this category. But also DTS-MA HD and Dolby TrueHD. All three of these formats are a revelation.
When I got my new home theater receiver a few years ago, I wasn't expecting a lot. I thought I'd have good sound, and was looking forward to hearing some BluRay Movie Sound to see what it was like. But I honestly didn't expect a jump in audio quality.
I was SHOCKED at the difference in audio quality. Even older movies, like Raiders Of The Lost Ark blew my socks off with the immediacy and "real quality" of the sound. I thought maybe it was just my new system, so I tried some good movies that had only Dolby Digital or (old style compressed) DTS soundtracks. Drumline is a good example. That movie has some really good audio. But with a compressed soundtrack, it was just not very good compared to an uncompressed soundtrack.
This is way off topic I know. I just wanted to share a little.
Brian.