What is the sound level of Your Listening Room?

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.

Not low enough. If you guys are getting 20dB, that is absolutely fantastic!