Well, using the Zoom M2 I generated a test tone @ 440Hz using Adobe Audition, recorded 30 seconds of it from loudspeaker replay, and then used the built in export function to normalise the recording and export to 16 bit and 24 bit (two rapid operations). Then I opened the exported files one at a time in Audition, replayed them, and noted the maximum level shown (and retained) on the meters. This showed that the file was normalised within the device to 0dB. Originally the peak value of the 32 bit float file was -11dB approx.
However, this exercise revealed a drawback in using the built in normalisation function. Right at the start of the recording there was some kind of transient click, either from handling or from pressing the record button. This was actually louder than the recorded tone. So the tone wasn't normalised as such - the click dictated how the whole file was normalised. If I had been doing this with real material I would probably have edited off the click in the DAW, and then normalised the actual wanted part of the recording. This might not happen all the time, depending on circumstances - I wasn't very careful about how I was holding the device when I recorded the tone, and as it's almost midnight here I replayed the tone at a modest level not wishing to disturb the neighbours. But it does illustrate a possible hazard in undertaking whole-file internal normalisation. But, it would give you something reasonably playable in terms of level, prior to further level control operations.
[Edited to add, while talking about this much maligned device - I just recorded some room silence using the M2 by the time honoured method of shoving it under a folded duvet in the early hours of the morning in a silent bedroom. I then examined the file in Adobe Audition. In the spectral frequency display there was absolutely no horizontal lines at all (which would indicate a noise band of some kind) and that was with the range cranked up to 210dB. Looking at the frequency display there was a maximum level of about -91dB at around 100Hz. This could be city rumble. At 1000 Hz the level was about -117dB and at 5Khz the level was -126dB. The level continued to drop slightly so that at 10kHz it was -127dB. Above that it slightly declined further. I doubt whether this amount of noise (system noise plus mic noise) would be of any real consequence or concern even in a classical recording - and it seems to me for the price of the device, it's nothing to complain about. I paid $117 US dollar equivalent back in December.]
