How loud is loud?

Digital audio provides a very good platform for dealing with things like Fletcher-Munson, when needed. Much better than old fashioned analog loudness buttons.

There is an unlimited # of ways audio CAN be processed digitally, many for good reason. Digital sound processing is the ULTIMATE sound quality tweak in terms of possibilities at ones disposal.

My preamp has zero adjustments for anything although I turn my sub up and down in a small range from time to time and that's all it needs. I assume people listen to different levels depending on how they feel (late at night I can easily enjoy listening at lower levels than during the day, regardless of ambient sound)...I simply use the "it feels too loud" adjustment criteria regardless of the content...I listen to a lot of jazz piano trio stuff these days and back the level off when the piano feels unnatural or like its poking me in the brain. When I noodle on my electric guitars (along with a rhythm track of some sort) I think I must play too loud all the time partly due to the "amp grease content factor", but it feels good so I don't stop.

For me, if something's hitting 100dB as measured from where I'm seated while listening, and not just for a brief moments, but with some regularity, that's loud.

loudness in dB SPL without stating the distance is meaningless. As you know, SPL drops approx 3dB for every doubling of the distance.
You wrote "where I'm seated while listening" - what distance is that from the loudspeaker?

For me 95dB SPL 10 feet away from the loudspeaker is LOUD. I try to keep my peaks at the 90dB SPL level (again, 10 feet from the loudspeaker).

It's about 10 feet, and yes, 95dB is plenty loud

Atmashere, Hi, when you put 2 pairs of 8ohm speakers on an amp that has 4 speaker post for bi-amping, what is the load drop from 8 ohms to?, is it 4 ohms?, less maybe?