NikosR, this gets into the issue of whether you let your application (e.g., Photoshop) perform the conversion from your image's RGB space to the printer's RGB space or whether you let the Epson driver do it.
1) When you let PS do it (e.g., choose Let Photoshop Determine Colors from the Color Handling menu in PS's Print With Preview box), then you need to disable color management in the Epson driver. This is performed by setting the Printer Color Management setting in the Epson driver to Off (No Color Adjustment).
2) When you let the Epson driver perform the conversion instead (e.g., choose Let Printer Determine Colors from the Color Handling menu in PS's Print With Preview box), then in most cases you need to choose ICM from the Printer Color Management setting in the driver. By choosing Host ICM, the Epson driver is simply using your operating system's built-in color management routines to perform the conversion (instead of using its own internal routines). You get to choose a rendering intent in much the same way that PS allows you to choose a rendering intent if you go with option #1 above.
If this doesn't make sense to you and you would like to keep life simple, I suggest that you stick with Option #1: Let Photoshop Determine Colors and set the Epson driver to Off (No Color Adjustment).