Since many people on this forum have reported better results wit cables longer than 1.5 meters you migfht think it would be the case with all cables.
However, we are talking about the Helix geometry with KLEI Harmony RCA plugs
The RCA plugs are what makes any SPDIF cable sound better, because with those you can get great performance even with a shorter cable.
Then factor in the Helix Geometry and you have yourself an extremely good cable
I have used Helix cables as a SPDIF link with the harmony RCA’s at 2 meter, 1 meter, and 0.5 meter, all identical wire and plugs and I could not tell the difference.
My last SPDIF was in my system for around 2 years and was the 0.5 meter version with
- Silver Harmony RCA’s
- SIGNAL: 1 x 24 gauge Neotech solid silver with Teflon insulation
- NEUTRAL: 1 x 16 gauge silver plated mil-spec wire
If I were to build one today, knowing what has been posted in this thread alone, I would probably fabricate as follows for the very best performance
- KLEI Absolute Harmony RCA’s
- SIGNAL: 2 x 18 gauge solid, bare UP-OCC twisted - inside a teflon tube
- An optional cotton sleeve over the Signal conductor assembly (personal preference)
- NEUTRAL: 1 x 16 gauge solid, bare UP-OCC with Teflon insulation
- and make it the length that suites your application
Alas, I have to rely on others like @wig , for their excellent feedback and observations regarding SPDIF cables because I no longer have them in my system
Hope that helps - Steve