87 (absolute) corresponds to THX Ref (OdBr). At that level, a 16 bit PCM input of -20 dBfs provides a calibrated 85 dB SPL at the listening position (note I mentioned calibrating the system).

I find I listen to films at approx -6 dBr (81 absolute) in a small room approx 2 1/2 meters from the LCRs, and most music at -20-22 dBr (67-65 absolute). Occasionally music is listened to at lower levels, particularly with CDs crammed up near 0 dBfs in encoded level.

Meridian Advocate