So, is the issue oscillation or noise (hum/hiss)? The 2Stroke amps I know of have neither as a problem, so it must be something in your construction or parts. It could be a lot of things, so here are a couple of guesses: Be sure that the non-electrolytic caps have the outermost shielding going toward ground. Check to be sure that the heater wires (twisted pair) are away from the other wiring. Ensure that the signal does not cross back over itself in the circuit. Double check that all leads are short in length. Check out Alan D’s 2Stroke chassis photo (the orange one) here on the TAN site. His circuit layout is clean, organized and exhibits correct lead dress. Note that the heater wiring is dressed away from the rest of the leads.