These devices include voltage regulators are part of their power supplies, by necessity. The can't work without them. The way a voltage regulator works is, once the input voltage exceeds the output voltage by a certain margin, the regulator is able to clamp the output voltage firmly to a specified voltage. The input may swing around above that threshold, but the output never changes. The second input voltage threshold is the maximum rated input voltage. If the power supply has been designed to accept input voltages resulting from mains ranging from 90V to 240V, then within that range the voltage regulator output would be constant within that range. Once exceeded, the power supply fails, or a fuse blows, which would of course affect the SQ. If the input voltage drops below the regulator threshold, it cannot properly regulate and operation of the circuits would become erratic.
External voltage regulators simply duplicate the function of the internal units and accomplish very little, certainly have no effect on SQ.