What is the proper loudness for listening?

In my listening room my speakers are 9 feet apart 3 feet off the wall and my listening position is 11 feet away from the speakers I have no side wall issues and vaulted ceiling  I have a very powerful D class amp 500watts@8ohm 650@4ohms and 1,200 watts@1ohm  I typically listen to music around 75db with peaks in the mid 80's  My amp really makes the inner detail and dynamics come alive compared to my tube amp  I'm afraid if I played any louder my neighbours would be on my porch with torches 

I have an Anthem STR Integrated amp and an Anthem STR power amp two speaker sets.  The Preamp preset volume by the factory is -35 on the "Volume knob".   Most often that setting is almost always good unless I am really jamming.   I do not have a Db meter.  The power and the ohm load and the speaker cone area give a good amount of presence. The SNR is very clean, likely class A.  I often listen to UHD or HD source or very good LP quality such as Miles Davis.   I tend to avoid low fidelity recordings, (most recordings).  Compression and noisy LP's have come to bother me so much that I limit my listening to such at below normal sound levels, if at all.  My 4 ohm Legacy 20/20 Focus speakers will put out the sound,but need 3 or 4 hundred watts.  My turntable must have higher end cart & stylus or the sound must be low volume.  Trash in, = trash out, the decibel level is not really the issue with me.

’Round here, depends where you are in it....at my desk, 70~75 is topping out a small ss amp, and loud enough in an 8h x 8d x 20w, doomed to the center cross-wise, ultra nearfield....50~60 good ’nuff.

Approaching a major physical space reconfig, so the main is down for a count....🙁

Major upheavals with good intents pending, but hope an improvement will fit into the mix.

Annd, there’s always the phones... ;)

I've noticed an unexpected but delightful increase in 'perceived dB' within a simple 4ch 'surround' with the Walsh.....something to improve on in the next 'condition'. *S*

Whatever you are comfortable with but be careful not to overdo 

Bravo barts, I agree. My system sounds best at 90-100db and does it easily at about 25 watts a channel. The key is very dynamic and bass heavy music. To each his own, but what I have come to expect from music is a connection that can only be had at higher volumes 80-100 dbs. As you said, the music and your ears will tell you what is enough.