I guess there'd be no need for a LPF on the output. Hmmm.. I'm not really sure how it works

Well, the output transistors in a class D or T amp are pulswidth modulated, ie fully on or fully off, for varying times - this is what makes them so power efficient compared to A or A/B class amps. By not running "somewhere in the middle" where you have both fairly high current through the transistor and a fairly large voltage drop over it, you get much smaller losses in the output stage - P=UxI.

It's effectively the mass of the moving parts of the speaker that reconstructs the low frequency signal out of the PWM high frequency switched signal. The cone can't follow each on/off transition due to its mass, but instead "follows the trend" in the PWM signal, ie the low frequency signal that was PWM'ed

/Michael