Input level,as in the actual sound from the pc?It sound like the input level on your computer is set way to high. Are you using the line in or the mic in?
What level is your radio set at?
What OS are you running. Windows XP, Vista or windows 7.
Is this a dedicated pc for the feed? and is the radio a dedicated radio for your feed? I would lower the recording setting on the PC for the MIC input to about 25% and have the radio at about 40% of full volume. Don't lower the radio to find the sweet spot. Lower the mic input and shut of the MIC BOOST if it is enabled.