While on the topic of DR...
Here's a pic of a Sony Metal Master with some Ronnie Montrose laid down on it.
Record over 20 years ago. Sourced from CD direct, with Dolby C with HX Pro engaged;
TC-K870ES
Shows just how good a quality metal tape, married with a capable deck and obvious wide dynamic material will preserve dynamics - not squash them.
The difference between the sustainable peaks and the running average, RMS level represents the dynamic range of the overall signal level.
Had this been a Type II or better yet, a Type I, the difference would be reduced significantly. On a deck with highly resolute metering, a cool
experiment is to record in steps: keep peaks at 0 VU for the first swag, then incrementally step up the recording level. As you bang up against
what the tape can handle for record levels, the DR *difference* will shrink. Just remember, meters are not linear; the lower end of the scale covers
a wider swath of dB range per segment. The optimum level to record at will be that compromise level between
maximum achievable DR, again the difference gap, with the least amount of perceivable distortion. The moral of the story? The better resolution (segment scale)
of the meters and wider the range (total number of segments), coupled with fast attack (visual response & reporting time) of any given deck,
the better job you can do to produce quality, well-controlled recordings.
Incidentally, I don't record at levels like this anymore on metal tape. No matter what a mfg specs as the max recording capability of a tape,
I strive to limit my peaking to no more than 4 dB now, quite often lower depending on the complexity of the source material while at the same time,
keeping the average - more constant level - in & around the 0 VU and Dolby markers. IMHO, this produces the most accurate reproduction. And don't forgot,
there's a reason that mfg's put those -20 dB response curves on the wrappers - because that is where you will get the flattest response out to 20 kHz!