Try new speaker cables like the Transparent Music Wave Plus (current MM version or previous version). The MF electronics are a little bright and the Synergistics may be highlighting the issue. The Synergistics are good cables, just not the right match for the MF amp.
If the speakers can be bi-wired and you are using the stock copper plates between the tweeter and woofer inputs, try using better jumper cables between the inputs. Transparent also make some good ones.
Chadlesko has a good point about isolation. The heavy gauge aluminum chassis of the MF has a high resonance frequency that could make the highs brighter. Using the Audioquest Sorbothane feet or the Black Diamond Racing Cones could help.
If the speakers can be bi-wired and you are using the stock copper plates between the tweeter and woofer inputs, try using better jumper cables between the inputs. Transparent also make some good ones.
Chadlesko has a good point about isolation. The heavy gauge aluminum chassis of the MF has a high resonance frequency that could make the highs brighter. Using the Audioquest Sorbothane feet or the Black Diamond Racing Cones could help.