3.5mm to RCA cable suggestions.

You're welcome, Asahitoro.  Regarding whether or not a power cord upgrade may benefit this particular speaker, though, I have no idea.  In addition to depending on the design of the speaker's two internal class AB amplifiers, and on the characteristics of its stock power cord, it could conceivably also depend on what the AC line voltage happens to be at your particular location.

Good luck.  Regards,
-- Al
 

ZU ones are very good and very cheap on ZU ebay site .

" Regarding proper grounding, I would expect that a stereo 3.5 mm to dual XLR adapter cable, such as the Hosa cable the OP linked to earlier, would accomplish that. Presumably it connects the ground of the 3.5 mm plug (the "S" of its TRS connections) to pins 1 and 3 of both XLR connectors. Pin 1 is the ground connection of an XLR input, and pin 3 is the signal pin that should be grounded when an XLR input is provided with an unbalanced signal. "

That's all true, but if a component has a balanced/SE switch, I'm pretty sure you still need to use it.

" Also, I’ve never liked 1/4 inch connectors because in my experience the contact they make can sometimes become intermittent, especially if they happen to be jiggled. "

Same here. Although I'm sure build quality makes a difference, but you don't get a choice on what goes into the component. Just the cable.