I have a denon D-M38 music receiver with matching SC-M37 denon speakers. I tried connecting a Wharfedale 150 subwoofer to the receiver. I have checked that the cables between the speakers and the sub are correctly set. I used a chord crimson plus audio lead to connect the connector on the denon to the input on the subwoofer. Again checked that the settings are correct. However I can get little sound from the subwoofer even if the volume is turned up to the highest on the reciever and the sub. Without the sub everything is working correctly. Am I using the wrong lead to connect the denon and the sub? A Maplin employee said it may be impedance related. Also I have read on the internet that the wharfdale and the denon are compatible. The deno is 30 watt. I am a newbie.