Amp choice?

I think there are better (and newer) options out there for the $$$ than those 2 amps.

So what are you choosing between again and what function do you expect the amps to accomplish? Your question confused me.

Are you sure you don't mean the Carver M400t cube amp? The M200t had a low profile rectangular shape.

I once owned an M400t, which btw is still going strong after around 30 years, in the home of a relative. When used with speakers having easy to drive impedance characteristics (i.e., not less than around 5 or 6 ohms at any frequency, and not having severely capacitive phase angles) its sonics were very respectable, and represented excellent value for the money. (The earlier non-"t" versions of the cube, though, were quite poor sonically IMO/IME). And it did seem fully as powerful as its 201W rating would suggest.

I have no knowledge of how well it would do, though, with speakers having difficult impedance characteristics. I see that the L1290 was rated as having a nominal impedance of 8 ohms, but I don't know how its impedance magnitude or phase vary as a function of frequency. And I have no knowledge of the impedance characteristics of the specific Paradigm Studio Monitor you are referring to.

I can't offer any comments on the upgraded Phase Linear amp. But if you can establish that the impedance characteristics of the speakers do not represent difficult loads, I would not hesitate to go with the M400t (assuming that is the model in question). And perhaps it would do ok even if the speakers are somewhat difficult.

Hope that helps. Regards,
-- Al