I also have the earlier EP500 with the brick-wall filter at 100Hz. This is fine since I use an 80Hz crossover with my M22s. The 150Hz provision(yes, it's my understanding that this should be on all units in the past three years or so)would only be of significance if very small speakers requiring a crossover above 100Hz were in use.
Yes, the drivers should be the same and the amplifier as well. One change made in the amplifier was to slow down the rate at which the volume control "opened up", so that a higher setting was used for the same volume level. This didn't in any way indicate that it was less powerful, only that a higher setting resulted in the same power.
