Speaker comparability with 2A3/300B SET is not just depends on the sensitivity of the speakers. Impedance curve of the speakers are probably more important than the sensitivity.
For example, you can use 89dB Merlins VSMs with 2A3 SET amps fine since they are 8ohm nominal with very small impedance dip. In other hand, another speaker with 94dB 8ohm nominal but impedance dips down to/below 4ohm will not work well even with 300B SET amps.
For example, you can use 89dB Merlins VSMs with 2A3 SET amps fine since they are 8ohm nominal with very small impedance dip. In other hand, another speaker with 94dB 8ohm nominal but impedance dips down to/below 4ohm will not work well even with 300B SET amps.