There are several factors that can affect the taste:

• The type of coffee can affect strength. De'Longhi recommends a good espresso coffee. Origin and blend (i.e. whether it is robusta or arabica), and the darkness of the roast affect strength.
• The grind may be too coarse. The grind can be decreased one notch at a time during the grinding process.
• Try increasing the strength of coffee on your machine settings which will increase the amount of coffee during the grinding process.