PLN has to choose between two masters that differ only in a high-shelf setting.
The ear is the authority on which one is better and this does not try to replace
it — but "which do you prefer" is a much easier question when you also know WHAT
differs and by how much, because a shelf change does not stay in the band it
names. It moves true peak, it changes how hard the limiter works, and it shifts
where the loudness normaliser lands.

So: integrated loudness, true peak, loudness range, L/R correlation and the
band-energy distribution for each file, then a delta table against the first,
because two absolute tables side by side is exactly how you miss a change that
matters. Band deltas are reported as RATIOS rather than differences in
percentage points: a band going from 0.12% to 0.24% is a doubling, and "+0.12
points" hides that entirely.

Measured on the RENDERED files, never predicted from the filter settings. A shelf
set to +3 dB does not necessarily put +3 dB in the master, since the limiter
downstream has opinions — feedback_verify_own_renders, the machine's job is the
objective facts so PLN's ears are spent on taste.

The smoke test proved the point immediately. Comparing the trial streaming master
against the harder-pushed club one, the loud version shows 0.92x the 60-120 Hz
energy and 1.08x the 300-1000 Hz: that is the limiter eating bass transients and
relatively lifting the mids, at a cost of 1.4 LU of range for 3.5 dB of loudness.
A measurable signature of what loudness costs, rather than a vague sense that the
loud one sounds smaller.

Wired into the finisher, so the summary PLN reads over coffee has the two masters
with their differences quantified next to the files themselves.