Among the finest sounding audio systems were those powered by medium powered Class A/B amps such as the classic McIntosh 225 and 240 (for mids alone-McIntosh MC30s). Generally speaking, low efficiency coupled with low impedance speakers require high powered amps such as most planar speakers to achieve adequate dynamic range. I had this problem when I owned stat speakers for 20 years. I have permanently moved to dynamic speakers of medium to high efficiency, despite lower impedance and difficult phase angles because even my medium power amps have great current capabilities and overcome the impedance and phase angle difficulties. 70 Class A tube watts is plenty for my efficient but difficult load (6 12" woofers) speakers in my average size listening room. 35 Class A/B tube watts is plenty for my easier to drive Legacy Signature IIIs in my living room (I auditioned them with a measly 17 watt Sherwood 7100 receiver).
Funny how whenever I hear Von Schweikert speakers at shows, they have extreme tube power amplification, often with $600K/4 power amps. Maybe for the huge rooms they play in. For the typical home listening setting, medium power is required. As to field coil and other benign speaker power requirements, low power amps will sound best and huge power amps would be energy wasters and possibly blow up the speaker.