Some things are very easy to adjust yourselves, such as the DC offset—requires only basic electronic knowledge, service manual (available for free online) and a voltmeter.
Others, like the Icq, are more difficult. The SM asks for a scope, a THD meter, signal generator and some hefty 8 Ohm 200W+ resistors. Unfortunately I don't have those, so I currently don't know whether my A3 is adjusted correctly. If I had it, I would set the Icq intentionally lower. Although this does not minimise the THD, it makes the output transistors dissipate less heat, which is positive on the longevity of the unit.