in my 40y + sound works I haven’t seen such speaker, with purely resistive load (2/4/6/8/12/16)! In order to design output filter properly, we need to take complex model of loading, including variety of speaker cables, DC protection relay ckt, speaker crossover, spkr driver/s complex, often resonating impedances, which is tremendous engineering task!
@westcoastaudiophile Actually its far simpler than that. A good class D amp can double power into a 4 Ohm load like any good class A or AB amp. There's no concern if the load isn't resistive! This is a no worries situation WRT the output filter.
In our case the amp is self oscillating, which means it also employs a lot of feedback. This prevents problems with capacitive or other odd loads causing resonance or the like- the amp is very well behaved with such loads as is any self-oscillating class D and so will be load invariant.