Are you running the receiver on battery or plugged in? I recommend the latter, to avoid pickup from the mains.

Next, look carefully at the output impedance and voltage of your cello (I am not sure all Yamaha Silent models are the same, or I'd tell you what I see on mine) and compare with the input impedance of the Boss transmitter, as well as its maximum input voltage.

If possible, test the Boss system with an electric guitar, since that's what the system was designed for. If you still get a buzz, it's either

1. interference from some other 2.4GHz source such as WiFi , or
2. the whole WL-50 just stinks and you'll need to give up :-(

Are you running the receiver on battery or plugged in? I recommend the battery, to avoid pickup from the mains.

Next, look carefully at the output impedance and voltage of your cello (I am not sure all Yamaha Silent models are the same, or I'd tell you what I see on mine) and compare with the input impedance of the Boss transmitter, as well as its maximum input voltage.

If possible, test the Boss system with an electric guitar, since that's what the system was designed for. If you still get a buzz, it's either

1. interference from some other 2.4GHz source such as WiFi , or
2. the whole WL-50 just stinks and you'll need to give up :-(