then that alembic thing sounds like it would be a dangerous weapon in the wrong hands
+1 to zoob's point that heavy EQ can put big holes in the tone, and if those holes just happen to be in the frequency range of a string, that string will sound weak.
my impression from reading about that alembic is that it's made to do weird things to the tone, with big cuts and boosts to the spectrum. if you're using it for a big low end boost, that will exaggerate your low notes and make your higher ones disappear by comparison.
trying to add a bunch of low end for the phil lesh rumble will also strain your bass cab and make the soundman's job harder. keep your tone even, and let the soundguy add the big sub frequencies if it works with the overall band mix.