Your 'path' parallels mine to a great extent since me n' higher math are 180 deg out of phase, so know the fundamentals of acoustics in very simple minded ways from experience and having been fortunate in knowing folks that could/did 'dumb down' the math enough to 'match' my viewpoints.
Basic horn theory is so simple that it was an anti-climatic realization since the math is literally 'Greek' to me in its symbols, complexity.
Regardless, T/S design theory only covers a driver's acceleration/rising response BW from Fs to its upper mass corner (Fhm) where the driver's mass controls its (flat) BW before its motor's inductance rolls off its HF BW.
Fhm = 2 x Fs/Qts' = ~544 Hz based on this driver's published specs.
[Qts']: [Qts] + any added series resistance [Rs]: http://www.mh-audio.nl/Calculators/newqts.html
[Rs] = 0.5 ohm minimum for wiring, so may be higher if a super small gauge is used as a series resistor and/or there's other series resistance.
