Class D

It's not an integrated but the March Audio P502 stereo amp is rated to 2 ohms. Sounds very good with Revel speakers. If you're looking for silly tweaks that either do nothing or degrade the amp look elsewhere this guy doesn't buy into the voodoo just gives a great performing amp for a decent price.

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?