Gregadd, I'll beg to differ with you on one point you make: "Tubes are too slow to get the speed out of ribbons." One of the reasons OTL tube amplifiers are so good with electrostatics is precisely their speed. OTL tube amplifiers have incredible speed throughout their frequency range, coupled with high resolution and transparency; the impedance of the speaker is the only issue in how good a match there will be (and with an OTL like the Atma-Sphere MA-2 impedance is not much of an issue unless it's dropping sharply below 3.5 ohms or so). Whether a ribbon will be a good match for an OTL will be a function of impedance matching, not speed. Since many electrostatics have rising impedance curves, and since OTLs are happier with high impedance loads than are solid state amps, it makes for a good combination. I just don't know about ribbons.
As to solid state versus tube OTL speed, I'd match the speed of an Atma-Sphere MA-1 or MA-2 to that of the best solid state amps any day, the solid state amps certainly don't surpass the Atma-Sphere as to "slew rate" or "rise time" (rated at 600 volts/microsecond, matching the Spectral solid state amps which exceed almost all others).
As to traditional transformer-based tube amps, I'll agree with you based on my listening, but I personally prefer any number of them to ss for other important characteristics.
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