Sorry for the late response - we indulge in "Amish Weekends" for our sanity. A remarkably refreshing break from being 'connected'.
If you have an attenuator on the amp, that is substantially different from what is on the typical active pre-amp. Without getting into a bunch of details, you are not likely to go into clipping at any volume via that attenuator. Not impossible, just not likely.
Then, tube amps clip softly. You may not notice clipping at the margins - the best way I might describe it would be as if the amp were 'breathing'.
Bi-Amping with another 120 would be an excellent response to those marginal issues. And Maggies are particularly suitable for bi-amping given their flat impedance curve.
I keep MG-111s, and in a very large room. So I have a very large solid-state amp to provide the headroom and transient response needed in that room.