Hi all.  Just finished my first build, a C-Lator.  Plugged in to test.  Works, but having it plugged in there is a hissing type sound added which is louder/quieter depending on the output volume.  Unplugging the C-lator eliminates this hiss, so its certainly coming from the unit.  Every now and then, you will also hear an isolated pop or crackle type of noise.  There is a pop sound when either of the bright switches are toggled, or when the standby switch is toggled.  Another odd thing is that if the unit is in the signal chain and it is switched to standby w/power still on, there is no appreciable change in the sound.  However, if I unplug the instrument cable from the input jack (while the unit is still in standby) and then re-insert the cable, the situation changes & no sound will come through until the standby toggle is switched back to operate.

I am completely puzzled.  Can someone help?
Thanks,
Mark