Information on how to increase the gain of phono level by 6dB or changing to line level is provided in the User Guide - see 'RIAA Input Options'.
This modification involves using a soldering iron to remove surface mount resistors.
If you are unsure of your ability to safely carry out this work then it is advised that you leave it to a qualified service technician.
For more information or to arrange modifications by a qualified service technician, please contact your dealer or local distributor.