I've just been given a Denon M35DAB which is working well however when switching on from cold the display lights and cd's will load and appear to play but there is no sound. After a minute or two a relay which I'm assuming is a protection relay will start clicking on and off and after about 10 seconds of morse code sounding clicks the system works fine. I originally tried this with 4 ohm speakers then realised it needed a minimum 6 ohm, same problem with both. The problem was there before connecting speakers so don't think they're the cause. Both pairs are fine when connected elsewhere. Is this a known fault with solution? If not any suggestion where to start?