They are, I spent many years "programming" FPGA's and microprocessors.. the speed of which digital circuits has increased means that digital circuit design and board layouts have to effectively have Analogue RF design principles in mind. I guess the question is much error(s) can one hear in the analogue domain once error correction and other design techniques have mitigated such errors ( if they exist).
My opinion is that such errors will only be audioable when said errors are large enough that error correction cannot resolve i.e. have you ever heard a badly corrupted DAT tape stream? CD Redbook standard for example has a large amount of bits for redundancy due to the Eight to Fourteen modulation technique for encoding to disc and employs CIRC error correction. Hi-MD used modulation was even less error prone due to utilising RLL1 and uses PRML a digital signal processing technique to extract the data from the disc from Intersymbol noise (digital noise). I have a whole book on the CD Redbook standard and it boggles the mind how much mathematics and signal processing is used and that's a 40 year old standard
So saying digital is digital is possibly a naive statement, but getting hung up on different digital cards producing a different sound IMHO is getting a bit silly.
