My own observations listening to recorded music is generally the higher the album recording level and consequently the level of volume attenuation I must use to obtain a natural sound level is proportional to the quality of "dynamic contrasts", or how well nuances are reproduced with varying competing instruments on an album.
On my audio system I find there's as much as 12 - 15 db's between the recording levels of many RBCD's and SACD's. And even within each type of media I find significant differences in recording levels. It does appear to me most classical albums are recorded with a lower recording volume, perhaps in part because massed instruments are harder to properly record.
I've read many pop/rock albums are purposely recorded with high volume levels to attract attention much in the same manner as commercial TV ads. But lately I'm also finding relatively high volume levels on jazz RBCD's and even some SACD's.
I can't understand why there appears to be no industry standards to facilitate good sound reproduction on albums, particularly non pop/rock albums. I'm not saying the album sound is unlistenable because it's the emotion of the music that's most important. But it seems to me it could be so much better on average if recording and mastering engineers would simply adhere to some industry standards.