hiss problem with mosfet booster

[hershey]

Hi all,
I built another mosfet booster from tonepad and works great. but there's massive hiss with power supply (One Spot). but when you `turn the pot up to 3/4 of the way the hiss dissapears. I saw this post:
http://www.elixant.com/~stompbox/smfforum/index.php?topic=21867.0
Would this be a similar issue?
thing is I've made a mosfet booster before without any issues with the same power supply thru same amp.
This build I used metal film resistors, wima caps etc to minimise noise.
thanks in advance