A lot of my favorite albums have a pretty varying range of master volumes, I've noticed. For example: right now, I'm loving Veneficum's album, "In Tranquil Absurd". The master volume = loud as shit. On the other hand, Death's "Human" album (another big favorite) is pretty low in master volume. The mix on each of those albums sound just fine; it's purely a difference in master volume.
When I'm mixing my own material, I try to minimize the red peaking as much as possible. I've managed to get as much master volume as I can out of my latest album, and in comparison to a lot of other albums, it's a hair quieter. And I'm quite satisfied with the final product. So the moral of the story is that if your master volume happens to be a little lower in comparison to others, don't sweat it. Unless it's completely absurdly quiet or ass-and-balls-shattering loud, people won't notice. In my opinion, there's a decent sized window of 'normalcy' when it comes to master volume.
Hell, most people don't notice a shit mix or a complete absolute lack of talent or musical decency too, but that's for another discussion altogether. But I digress.