What Volume do you listen at?

Of course the perception of loudness is one of the most misunderstood and neglected areas of sound reproduction.
The presence of noise and distortion adds dramtically to the perception of loudness. A less resolving system will tempt you to turn it up.
Thus my car and mini-system appear louder than my main sytem. Moreover my main has excellent low level resolution(vital for apartment living0
If you have ever lived with an aspring musician you will find ther is almost nowhere in the house where you can't hear them practice.
Live music requires almost no amplification. Your real challenge is to purchase equipment with low noise and distortion. Your desire to "turn it up will decrease.
The next step is dynamic range. Very important. I search for a volume that allows optimium resolution but still leaves sufficient headroom so you can hear dynamaic contrast.

According to my RatShack SPL meter, I listen between 50-70. Anything above that and it just hurts my ears.

Years ago, I made a post here about volume level, the main thrust of which was that for any given piece of music there is only one volume level that is correct. I, obviously, didn't invent anything here as this comes from a recording engineer of some repute. I had even postulated that every record should have some built-in benchmark indicating what that proper level should be.

You are right on one thing: a better system will be way more dynamic and, while the average SPL might be similar to what to you get with a smaller system, the uncompressed dynamics is where you will get your money's worth.

A dedicated listening room is really a must for serious listening in order to keep some semblance of peace in the house.

My guess is that when you have High End gear, you naturally want to play the music at a higher volume.

I've found this to be untrue, especially with fully acoustic music. If the system has good resolution, dynamics and a low noise level, the urge to crank it up actually decreases in my experience.

However, if you are into head-banging rock at live concert levels, maybe you have a point. I don't enjoy the jet-engine sound level of many live rock concerts so I certainly have no urge to recreate that in my home.

However, if you are currently listening at 75 or 80 dB it sounds like you're in my league. I doubt that you'll be turning things up with a new system. Hopefully you'll just be enjoying it more.

The basement is the way to go, assuming you can AC/Heat it and that that equipment can be isolated so as not to provide a nasty 'noise' floor. That being said, what you are looking for is 'live' music levels of volume. Everything else becomes just background music, and Bose can take care of that without spending $30K. When I built my last house I created in the basement a custom designed listening/media room. High WAF, live music/movie listening levels that could not be heard outside the room, no comprise with speaker placement. You can tweak forever. Looking at your picture I see the 'wife' every where, it will never work, especially with all the glass. Believe me, living rooms are like 'dressy' dresses, and you know who rules there. A small tip if you are going to the basement, put a two inch exterior, heavily striped door at the main floor entrance door to the basement. Also use these type of door every where a door is needed in the basement space. Look into Armstrong Wave ceilings and put heavy carpet on the floors and achieve a 'dead' room, then all you hear are the speakers without any room colorations. So, spend $10K on the room, and $20K on the equipment. You will never regret it.