Yellow
The only reason I tried HM7000 was because I couldn't justify the cost of the expensive sound decoders . I have a few fitted with zimo and lenz sound decoders which came pre fitted but to be honest I really can't tell much difference in the sounds. I am not a fan of the speakers that hornby supply and always change them for esu speakers. I also have about 20 fitted with tts decoders regards John