What is the best digital cable?

As you know, "best" is very subjective. I sure like the Stealth Varidig -- I have the 1.5m balanced and the sound is very clear.

for me, the really best ones on my system are:
syn.research squared ref.,xlo LE.,kharma grande ref.
for my taste ,i maybe love kharma more than others,
i did not try but people says siltechs new g5
digital cable also is very good.
some dealer and factory say that digital cable must be 1.5 meter and never less than 1 meter

I compared the Madrigal AES/EBU directly to the comparably priced Cardas (each about $300. MSRP) AES/EBU-- each one meter. The Madrigal was extremely detailed but lacked pace, rhythm, and timing. This was between ML 37 transpot and ML 360S DAC. The Cardas did not have the detail of the Madrigal, but PRT is excellent and thus it is much more musical. I own the Cardas. I too doubt you could tell .5M from 1 M length. Good Luck. Craig.

I'm using a Nordost Silver Shadow 0.5m between my
Levinson 37 and the TacT RCS 2.0. Seems to work well.

There is no "best". Period. Depends on your rig. I like the Purist. Terrific dynamics. Price is terrific too....