You problem is that the Tone hammer is 18 volts, Your hitting it with 9, half. Way under current means no headroom and noise. You'll have to use 2 power supplies a 9 and an 18volt.
My soap box on 18 volt pedals. There is a chip that cost about a 1 cent that can take 9volts and step it up to 18 volts. It's common and in a lot pedals and other electronics.
The Visual Sound Visual Volume actually runs 18volts on a signal 9volts battery, because of this chip.
There's only one reason for not using the chip in a circuit. They want to sell you a $30 power supply that cost them $3 to make.