I've had very good experiences with coffeearoma also. :-)
Your bean choice is definitely a limiting factor, first and foremost. Try to find a local roaster who is using decent beans. Ask in coffee shops who serve exceptional coffee for their beans. Make sure they're fresh! Roasted coffee is good for 2-3 weeks, typically, so nothing you get in the supermarket will be much good. Good coffee should have the roast date printed clearly.
Beyond that, how is your pour looking from the naked? Are you getting a steady stream from the centre? How much volume do you get over what sort of timeframe? I have the same equipment and I use grind settings from 7-12, depending on the bean. I aim for 25-30 second pours, and usually have them a little tighter than most people and end up with 30-40ml doubles. That's more a matter of taste though.