Sibilance

[Kiwi]

Hi Guys.
I have had my MAX PRO 1 up and running for about a month now. I have an LPFM station in New Zealand and by law can only run on 0.5 a watt. I am still testing everything at the moment.
My question is. I have a problem with sibilance. As far as I can see, my Radio Automation Software is working perfectly, with the Dynamic Proccessors balanced nicely and the EQ settings are all set flat. The Sound Card is compliant with the Automation Software, the transmitter settings are all set correctly and the arial is fine. Basically everything is set up correctly and running fine except for the audio sibilance. However, the sibilance problem is random. It can be heard on/or not, on any type of stereo, whether it be on a quality system or a small transistor. I know the variation of problems could be many but could this possibly be a transmitter issue.

Regards. Kiwi