Running 4 ohm speaks on bridged amp...ok?

I agree with Daniel. I used to own a pair of Acoustat 4 ohm speakers and my old Bryston 3B amp would run out of steam. I asked Bryston about bridging in another 3B and they advised against it saying that the 4ohm load on a typical elctrostat would be too hard on the bridged amps. They suggested getting a more powerful 2 channel amp which I did - 4B-ST. Then I sold that stats and replaced them with Maggie 1.5's - never had a problem yet. I know that the 1.6's are 4ohm and while they do have a relatively flat impedence curve rather than bridge I would either bi-amp or upgrade the amp to one with more power at the 4 ohm rating - Bryston 4B-ST, bigger Classe like CA-200 or 201, Aragon 8008, Marsh A400 to name a few...

Huh? Bridging the amp doesn't change the speaker's impedance. I would suggest contacting Classe and asking them if the amp can drive a 4 ohm load properly. However, if it's driving them now, it should still do so bridged.

It's true, bridging does not change the speaker's impedance
but since each channel of a bridged amp drives half the wave form, it sees half the speaker's impedance. Most manufacturers of 4 ohm (or less) speakers advise against bridging. However, some amps will drve any load so it is best to check with the amp manufaturer.

One more time. The speaker impedance indeed remains the same (just like the song). The outputs of the bridged amp are in series, driven from a single input. This effectively doubles the output voltage swing driving the load (speaker) for a given input level. Thus the current requirement at any given input level is essentially the same AS IF the unbridged amp were driving half the load impedance in a two-channel configuration.