I have never had an RCA cable fail or give me an error message when using my PMD 661. I have lots of great digi cables including ones made by DigiGal, Darktrain and Ted. They all are great frankly, but the truth is I pretty much always use a skinny flexible cheapie phono RCA cable, because it is flexible, and does not care how I bend it and it. This allows me to place things in my bag where I want them versus where the cable wants them as you probably all know what I mean
. I know this may fly in the face of the logic in this thread which is very sound from people that know their stuff. I run my cable between my Marantz and a Sound Devices USB Pre2. Is it possible that the preamp the OP is using could have something to do with the error and impedance fussyness, and the deck at the end of the chain is merely reflecting this? I just thought I'd share my experience and see if it helps lead to a resolution. My deck still has the next to latest firmware, not because I'm concerned, but because I just have never remembered to update it.