What high efficiency speaker for Classical Music ?

[mashaffer]

Which brings me to the other point.
classical music reproduction is pretty much hopeless without 4 channels.

Unless you have a couple of rear speakers also involved, to bring in decent rear ambience (low level), most stereo recordings sound pretty flat, and this from years of experience (we also made some highly successful live surround sound recordings).

This rear info is low power, ideally suited to SET type amps of low power.
This makes front channel info far less critical, and reduces the need for generally higher powers.

I use some omni rear speakers for this, for which a 1-3W amp output is entirely successful.

My experience has been that open baffles give a very credible sound field, far from hopeless IMO.

 

[GM]

As I understand it, the higher Zout of the SET amp raises the Q of the total system (amp+speaker), so you get a bass boost.

........and HF as it's also 'tracking' the rising impedance due to its inductance = 'smiley face' EQ.