Digital input selection

SPDIF is an analog and digital RF signal that carries both digital data and analog time reference information. Ideally it should be treated as RF, with any impedance discontinuities minimized. An RF rated relay could perform pretty well. A crude and sloppy switch arrangement might cause some problems, depending. However, for a cheap dac with marginal performance to begin with, technical details of proper switching might not make much audible difference, again depending.