Class D

I have Classe Sigma Amps - they sounded exceptional, but they could not drive the bass on my Wilsons.  I had other amps go into protection at concert levels (Bryston / PS Audio).  I moved the class D's to surround duty and put Rowland Monoblocks in to drive the Wilson load which can dip to 1 ohm.  Pure bliss.

@tweak1
Well, not that I’m aware of what you suggest, as his review speaker were SIBELIUS of 87 dB.
Those Mola Mola monos are supposed to ’do’ some 400 odd watt/channel (into 4 ohm...) - somewhat more than my X350.5 Pass.
So - no go with my power saving notions.
This issue is/was some often mentioned with class D amps, and can strip music of its musicality. 
Was happy to go back to my present set up.
Michélle 🇿🇦

My 4 ohm Apogee Duettas were driven very nicely by a pair of Bel Canto Ref 1000 monoblocks. I'm sure they would work fot you Zappas.

What's wrong with getting a competent Purifi-based class D power amp from Apollon, March, Nord, etc., and then sticking a nice tubey tube preamp in front of it?

I hooked my $80 Fosi integrated amp (with Bluetooth) to a pair of kef ls50s and have been frankly flabbergasted how good it sounds.  I have heard some highly regarded “audiophile” amps totally strike out with those.  
Just saying.  Can’t go wrong for the price that is for sure.   Returnable off Amazon and nothing to lose to try for peanuts by high end audio standards.