The problem I had (REW 5.12, Ubuntu Linux 14.04 LTS) was simply nowt out! Nothing from the generator, either on the meters nor the physical output, no clicks, nothing to anywhere (speakers, headphones, external soundcard, PulseAudio, default, Codec...). And no error messages. But the input department appeared to be working fine.
Solved as above by removing Open JDK Java 6 & 7 runtimes and substituting the full-blown Oracle Java 8 instead.