PA15A/PA20A Series E sound output?

I'm curious: how loud are the Federal Signal PA15A/PA20A Series E electronic sirens (also including variants such as PA150/PA200, etc)? I'm particularly interested in how loud they are with 58-watt speakers vs. 100-watt speakers.

 

[Wailer]

They operate at 58 watts with one speaker or 100 watts with two speakers.

If you hook up one 100 watt speaker the siren will still operate at 58 watts.

 

[Night Patrolman]

They operate at 58 watts with one speaker or 100 watts with two speakers.

If you hook up one 100 watt speaker the siren will still operate at 58 watts.

Sorry, I should've been clearer. I meant how loud are they. For example, it's said that the Q series mechanical sirens put out 123 decibels at 10 feet, so that's what I'm looking for for these sirens.