Check if startach doesn’t have integrated null modem capabilities. I have a feeling that it does.

If it does you just use the appropriate gendered cables with straight through wiring - null modem is crossover just like between ears and mouth.

Meridian owner since 1992
Prime & PSU, Focal Elear headphones, Roon (ROCK 8Gi5 NUC), Explorer 1 & 2, F80. 200/203, various Sonos (via Roon).