I have tried my Ori with 5 SS amps/preamps, and 4 of the 5 sounded wonderful (though somewhat different from each other):
- Violectric V281 (balanced & single-ended_
- Lake People G109-A (single ended, made by same people as Violectric)
- Audio GD SA-31SE (balanced & single ended)
- Liquid Carbon (balanced and single-ended)
The Audio GD has double the power of the V281; and the V281 has double the power of the others. However, the subjective experience of all that power is not exactly linear/predictable. In fact, all 4 units have more than enough power for the power-hungry Ori. By "more than enough power," I mean not only can you get it way beyond painfully loud--but it sounds terrific the whole time.
Simply getting a planar design to full loudness doesn't necessarily mean it will sound good. My 5th amp/preamp, the Matrix M-Stage HPA-1 (which has a very nice basic sound), just couldn't get the Ori up to speed. It got very loud, but sounded stressed at all volumes.