If problems are experienced in accurately setting the output bias current to its correct figure of 25mA (e.g. 10mV across 2R158, 2R159, 2R258 or 2R259) because the range of the control is restricted or compressed then adding a 470R resistor in parallel with 2R155 and 2R255 should help. Also ensure that there is plenty of heat sink compound around 2IC101 and 2IC201 so that they are adequately coupled to the output transistors, this is necessary for stability. [Beomaster 1100]