Hi Tom, if I understand your situation correctly, there is no way to highpass filter the signal before your Krell amplifies it and sends it to the Maggies.
Theoretically you could roll off the bass going to the Maggies by placing a highpass filter in between your amp and the Maggies. This may or may not be a net improvement.
FORTUNATELY we have Stereophile's impedance measurements of the Maggie 1.6qr, which makes the necessary calculations possible.
The impedance of your Maggies is amazingly smooth across the bass region, and I estimate that it averages about 5.3 ohms across a two-octave region centered on 80 Hz. For a second-order 80 Hz highpass filter, I'd suggest about 265 microfarads of capacitance with 15 mH of inductance on the shunt leg. NO electrolytic capacitors allowed. I do not suggest a first-order filter because a) it will have too much effect north of the crossover region; b) it will not protect your speakers as well; and c) it probably would not blend as well with the lowpass filter in the SA-1000 amp.
IF you end up with a bit too much output from the Maggies in the crossover region, I suggest reducing the amount of capacitance and just leaving the 15 mH inductor alone. If you need a bit more output from the Maggies in the crossover region, I suggest increasing the amount of capacitance and again leaving the inductor alone.
No guarantees of course that this will be a worthwhile net improvement. My advice is free and worth EVERY penny.
Duke