I have downloaded and installed REW 5.19 beta 6. I am using Linux Debian 8. The installation went well and I can open and run REW. However, when I go into preferences and select the Benchmark DAC1 as output, it doesn't seem to work correctly. If I click on Check Levels and then Next, one of two things happens. Sometimes I hear the noise coming from the speakers but the level indicators remain grey and at -99. After a short while the noise stops and the left level indicator turns to colour but the test has stopped. Other times the noise sounds very briefly and the left indicator shows the level but only for a second or so. Then the noise stops and the indicators go grey again. The log file shows the following error: Exception in thread "Thread-6" java.lang.NullPointerException at roomeqwizard.GC.h(Unknown Source) at roomeqwizard.GC.run(Unknown Source) I looked at the soundcard_debug file and the DAC seems to be listed correctly as: B10 [plughw:1,0], ALSA (http://www.alsa-project.org), 3.16.0-4-686-pae, Direct Audio Device: Benchmark 1.0, USB Audio, USB Audio If I select the internal sound card and perform the check, I get a constant noise coming from the laptop speakers and the left indicator flickers up and down a bit around -12dB which is the level set for the sweep. This continues until I click on Finish. I assume this is the correct behaviour but I need it to work through my DAC.