@stuartk It usually is always better to follow the KISS principal. (Keep it simple...)
Adapters, while they work, sooner or later can cause problems. The extra connections on the signal path, potentially cheap construction, and potential impedance mismatches with adapters...
So, +1 to carlsbad2 and audphile1, get either a good coax/spidif cable (RCA's) or and AES/EBU.
my 2 cents...