Class A Amp

Rleff comes closest to what you want with his recommendation of the Atma-Sphere. Keep in mind that Rleff discribes only one channel. Check it out on atma-sphere.com, it's really a product to behold!

What 2.8 Ohm load speaker specifically?

If the load varies widely by frequency around a 2.8 ohm average spec, then I'm thinking any tube amp, even the Atmasphere, may not be ideal.

I'm thinking one of the other Class A SS recommendations, assuming they double output from 8 into 4 and 2 ohms, or the Rowland or Bel Canto Class Ds that do same would be better.

Most class A amps go to class A/B after 20-60 watts. They simply can't dissipate that much power when idle. I'd go with a moscode bridged mono.

I'm a fan of the Moscode amp, but the dink on it has been a weakness driving low impedance speakers, so I'm not sure it's the best choice for the OP.

Perhaps the new Moscode 402 has improved upon this?

I remember drawing similar conclusions as Tvad regarding driving low impedance loads when researching the Moscode.