The AGN II speaker system build

[_Scotty_]

No doubt about that, microphone and associated gain stage overload are a thing. From a SNR
standpoint, the recording is very good.  How loudly did seem it like you had to playback the Saint Saens piece to achieve the recording level you had?
 One of my biggest gripes about my UMM-6 USB is it's relatively poor SNR
of -70dB. It could easily have a -95dB or better SNR.  At this point in time the chips are out there and they are inexpensive to use. You have to playback your test signal using REW at very loud levels to overcome the
the ambient noise of the room and the -70 SNR of the measurement microphone. The power levels necessary
are somewhat concerning especially in a larger room with potentially insensitive loudspeakers.
 I would think that if the microphone had a better SNR you would only have be above the ambient noise by 10 to 20dB.
This could result in your test signal being no louder than 70 or 80dB at measuring position. Perhaps a little safer for the health
of your tweeter.
 Correct me if I have the wrong assumption regarding this topic.
Scotty

[HAL]

Scotty,
The peak SPL level in the room was probably around 85dB SPL with the Saint-Seans excerpt. 

I run sweeps in the 70dB SPL range for the planar drivers for protection and the spaced in time for heat dissipation.  The room noise floor is below the mic noise floor of the Beyerdynamic MM1 measurement mic, so lower than the GoPro mic noise.  The LM10n planar drivers are rated at 70Wrms as long as out of band low frequencies are used.  There is no tweeter in this case, just the wideband planar.

The camera does have very good stereo recording capability when I listen to the original WAV files, but MP4 for video is compressed and that is the standard.