Do you have suggestions for other amp pairings with the Wilson Sabrinas? I am open-minded at this point.I suspect that Knghifi’s suggestion of the VAC 200iq would avoid the concerns I expressed about pairing the Sigma with the Sabrina. Especially if two of them were used as monoblocks, but possibly also using just one in stereo mode. I say that in part because the 200iq includes a third output tap, designated as being for 1 to 2 ohm loads. That in combination with the reference in its description to 6 db of feedback suggests that the output impedance of that tap is low enough to avoid the tonal issue I referred to. It is also more powerful than the Sigma, of course.
A risk of going that route, however, would be the possibility that having a preamp in the chain might ultimately prove to be sonically desirable, and a preamp that would do justice to the rest of the equipment would add up to very big $ in combination with two or even one of those amps. See this thread for some discussion of using the Aeris with and without a preamp.
From a technical standpoint I would also expect something like an ARC Ref150SE to be a compatible pairing. ARC tube amps tend to have lower output impedance than many or most other high quality tube amps, as well as having very robust power supplies. However its size, complexity, heat generation, cost, and again the possible desirability of a preamp may rule it out. And I have no knowledge of how well its sonics would synergize with those of the Sabrina.
I’m not particularly knowledgeable about VTL products, but the fact that most of their amps have only a single output tap, nominally rated for a 5 ohm load although claimed to be suitable for 2 to 8 ohm loads, would give me pause.
Regarding Rowland solid state amplification, I have no experience but FWIW a number of members here whom I consider to be particularly credible, including Ricred who posted above, use it with great results. As far as I know there are no technical issues that the Continuum S2 or the Rowland power amps would present in your application.
Good luck. Regards,
-- Al