From the manufacturer website (https://audiowise-canada.myshopify.com/products/dx-optical-isolation-kit):
"Hear your DAC as it was meant to be heard. OPTO•DX™ is the superior remedy for RF noise in a single or dual-coax SPDIF interface. It works by modulating the SPDIF signal to optical and back to SPDIF over an optical bridge for total optical galvanic isolation. Further, OPTO•DX has independent 12VDC inputs for each side of the optical bridge to provide complete power isolation and reduced noise using battery packs or low noise supplies.
"While cleaner sources, ferrite-laden coax cables and other tweaks may attenuate RF noise to the level of your systems’ subjective noise floor, OPTO•DX provides an objectively superior solution for those with the most revealing systems and highest appreciation for musical transparency. With OPTO•DX you will hear a more perfect D/A conversion: a less bright, smoother presentation with more subtle details revealed - and you can listen louder and for longer without listening fatigue."