I have Innuos Zen mk3 and I prefer Inakustik Referenz usb over Curious. It gives better bass response with more detail and woodly,heftier notes in acoustic bass but not bloomy, and better sense of naturalness/realism.
You know as with some cables you hear more how strings are played and others bring more resolution to hear how actual instrument resonates,better balance. Also there is more realistic prat,tone and nicely refined,compact soundstage. Just more fun to listen with better separation from top to bottom without listening fatique.
Inakustik is copper cable with all transparency that silver used in Curious with benefits of copper in meatier,better delineated human voices and crystal clear top end and great dynamics and speed. I was quite surprised when I tried it after Curious because I felt Curious was a keeper and better than anything else I tried before. There´s always something new and better ( different ) behind the corner.
It´s always trial and error to find best balance,so there are no free lunches as what´s best. Only many good choices to pick and try…
Sure that Shunyata Sigma is a killer ,for the price it should be