Using a typical power soak (attenuator), between the OT and speakers, and cranking the amp, actually does drive the tubes harder with much less output volume. So, of course you lose a bit in tone/feel because the speakers aren't putting out as much volume, but you can get the driven tube tone at lower output volume. Unless anyone has the schematic for the RA, or someone examines the inside of their RA amp, we don't know exactly what MB means by "power soak". Is it an attenuator between OT and speakers, or some other circuit addition that simulates an attenuator? If it is an attenuator, the tubes will be driven harder, that is the whole point of an attenuator.