Here's the general idea for modifying any cheaper commercial product. Open the product up and take notes of where the power supply as well as the analog path are and what caps and locations are involved. Write down the voltage as well as the capacitance of each cap you wish to replace. Then, increase capacitance values by 50-200 percent depending on placement and what will fit. The main caps you are going to want to change are in the power supply, as this will make the biggest difference. If you are bypassing the analog op-amps, then do not worry about opamps. If not, then that's a whole other ballgame and will require a bit more soldering skill.
Apply dampening to the chassis as well as the physical transport top reduce vibration. That my friend's is the basic mod. Lots more can be done, changing out diodes to hexfreds, clocks, etc, but that is mucgh more machine specific. That said, if the unit doesn't sound good to begin with, don't waste your time and money.
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