How to connect an internal “ESI Maya 44ex Soundcard” with “Presonus Eris 3.5 gen2” PC-Speakers? – Computer Setup and System Configuration Forum

I’d take a 6.3mm Y-splitter cable with one TRS on one side and two TS on the other. Just plug them into the balanced inputs. It shorts ground & cold, but that’s ok. Never heard it’s not ok, but it might give a 3dB quieter signal.
Otherwise: insert more adapters or get out your soldering kit.

But do consider how far your monitors are apart.
So best choice is one short stereo -> dual-mono splitter and two 6.3mm TS -> RCA cables.

Also do check manuals: are the expected levels the same on balanced/unbalanced inputs of the monitors? Is it consumer or pro level on the interface outputs? +/- 4 or 10 dB or so is the difference.