+ yogiboy.
I searched to find the effective mass of your tonearm and cannot find it. The problem with the ART9 is that it has a very high compliance rating of 32 @ 10Hz. That would mean it should be matched with ultra low mass tonearms to avoid unwanted and very low resonances. That could explain the tubbiness in the bass. Your arm does not look to be ultra low mass and could simply be a mismatch.
The compliance rating of a cartridge does matter and cartridge manufacturers seem to take it more seriously than tonearm manufacturers as both specs must be known.
I searched to find the effective mass of your tonearm and cannot find it. The problem with the ART9 is that it has a very high compliance rating of 32 @ 10Hz. That would mean it should be matched with ultra low mass tonearms to avoid unwanted and very low resonances. That could explain the tubbiness in the bass. Your arm does not look to be ultra low mass and could simply be a mismatch.
The compliance rating of a cartridge does matter and cartridge manufacturers seem to take it more seriously than tonearm manufacturers as both specs must be known.