What is the sound level of Your Listening Room?

I built my room custom to ensure noise diminishment. With dehumidifier going outside the room and AC running, 23dB. When neither is running, 16dB. 

I'm in the process of building the music room, lowest level on one side of a split-level on concrete but mostly above ground.  Reframed with 6" wood wall studs then sprayed with open-cell spray foam (all surfaces).
Then SAFB and finally Quiet Rock.  Empty room as it sits right now, save for a shop vac.  With the NIOSH app on my iphone I get 18dB.  This is with no rugs, curtains or acoustic treatment. Funny that at that level of quiet even a very slight stomach burble bounces the app up to around 21-23dB.

wolfie62,  power relates to the quality of the sound, not the relative listening level. It has no bearing on the issue of ambient noise in the listening environment. You could use a cheap 50wpc amp or an expensive 1,000wpc amp, and the environmental noise issue is unaffected, given that the amps are quiet. Power is irrelevant. 

Perhaps you could do a little test to learn about ambient noise masking the signal. Take your audio system outside. Play it while the neighbor is cutting grass with a lawn tractor. 

Is the lawn tractor masking the music? Ah, then you obviously need a 1,000wpc amp! That should fix it all, right? Obviously, power makes the ambient noise go away, right? Or, perhaps you were simplistic in your assessment.   :(

Having a quiet listening space allows for appreciation of nuances such as the difference between a noisier vintage tube amp and a newer, more absolutely quiet class D amp, such as I wrote up for Dagogo.com, the i.V4 Ultra from Legacy Audio. It would be a bit tougher to hear those distinctions outside with the neighbor's lawn tractor running. But, relatively easy to hear such distinctions in a quiet room. 

Please do not disdain what you do not understand!  :) 

barts, congrats on what will be an excellent environment! Kudos! You will LOVE the solitude! The music will be stunning in such a space. 

Yes, when I breath heavier, the meter jumps by a couple dB. 

This morning I got an average reading of 18.4db
with a low of 13.8db in my living (listening) room. I have an acoustic ceiling in the living room. It’s not an open layout. Hardwood floor and giant Persian rug.

I think old houses with new windows may be quieter. Quiet neighborhood does help.

I do hear faint road and freeway noise and the quartz wall clock ticking.