Jim, what sound card are you using in order to playback audio outside of Sonar? If you are exclusively using the M-audio in Sonar and a second sound card to play audio in other applications then, it could be the M-audio. Regards, Phil Muir P J Muir Productions Music and audio production URL: www.philmuir.com/ ----- Original Message ----- From: Jim To: ddots-l@xxxxxxxxxxxxx Sent: Sunday, June 11, 2006 9:25 AM Subject: [ddots-l] noisy sonar Hi List, Every time I launch sonar I get a low level pulsing hum. I thought it might be my M-audio fw 4-10 sound card, but when playing other sound files, everything sounds clean as a whistle. Could this hum be something to do with my pc? Best wishes Jim McAuslan from sunny Findhorn Minds are like parachutes, they work best when open.