sylpheed-port disqualified a difference instrument of their own and named the rule:
before asking whether an instrument can measure a difference, ask whether it
returns zero for no difference. Mine had never had that test -- its positive
control was a filtered copy at 0.94, which I had taken as the ceiling.
Identity reads 1.0000 in every band, and a linear filter with NO delay also reads
1.0000. The 0.94 was entirely the 12 ms delay's windowing cost. So the ceiling for
a filtered copy is 1.0 and the measured 0.027 midrange is further from it than the
original control implied.
It also adds an argument the first pass missed: a delay depresses coherence
uniformly (0.9288..0.9380 flat), while the measurement is 0.027 midrange against
0.83 at HF. The shape is inconsistent with a delayed filtered copy too, which was
the remaining route by which a rear pair could have produced it.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Wuu56cE8vJGTBtn1ppsk8v
c7d8b2e21c