Monitor SPL vs. Full-Range SPL

If I am not mistaken I believe white noise is used when a speaker's SPL in dB/M is measured. This means the speaker level are equal at any frequency its capable of.

I think you are confusing sensitivity and SPL. SPL is nothing more than a unit. Either the speaker in question can produce a certain number of units or it can't.

80 db is 80 db regardless of the speaker producing it.

There are some stand mount speakers that because of their drivers and design are capable of more bass output than some floor standers. How much power it takes to get there is a different situation, and that's where sensitivity comes into play.

I'll add only this, as freq's go down, you won't hear them as louder...probably, you won't hear them at all.

Deep bass is felt more than heard.

Dave

The point is, if a speaker has increased bass output because of increased FR range overall SPL will be higher. Consider this, if speakers are set to 80 db playing a 1kHz test tone, SPL will not be the same when playing white noise since the full range speaker plays deeper in the bass (audible or not, it will still measure on an SPL meter).
I am thinking bright speakers will be played quieter since subjectively they sound louder since bass notes are not heard but more felt.