Not sure how your Audyssey works but I know with my YPAO I used it to establish PEQ parametres but I still manually set my speakers with a SPL metre. As for the gain being set -6dbs it really depends on the sensitive of your subwoofer and room placement. I'd use the SPL metre and set everything to 75dbs. As for a more sensitive subwoofer it could appear to be louder at a given voltage input than a less sensitive one set at the same input or level. That's why using this method allows for proper set up regarless of what the level is set at...I hope this makes some sense...
As for the pb12 its a decent sub and should probabaly give you more pucnh for home theather applications...IMO. I've audtioned the Energy s12(same as the Mirage s12) and the Svs dug much deeper.
Regards, Bill
