What is the proper loudness for listening?

I agree with Paul McGowan. I don’t pay attention to db levels as my guide. My guide is what the particular music should be played at to be in proportion if it were live, and per where I am ‘sitting’ for the performance. Of course, I play a lot of acoustic music, where that is more easily defined in ‘size’.

The db levels are informative to a point. What’s the ambient noise level of your room?

I don’t have to listen LOUD to get it, but if I crank it a bit more than mild, I’ll energize the room with the subs and can get more. It is not necessarily better, I listen to tonality, texture and a "filled in" dimensional sound- I usually start with the midrange anyway, if that isn’t grainless and transparent, I’m out. But in terms of volume level, depending on how loudly a particular level is cut into a specific pressing, there’s an ideal loudness level within a range. Beyond that, you aren’t going to get more. Is it a system failing? if so, I don’t care at this point.

Be happy, don’t worry. Or something.

Play it really loud and go outside to listen to it...as Neil Young yelled, "more barn." 

Until the police is knocking at your front door

I have found 80-85 DB is best in my room.