About loading, the current drawn by a circuit is given by ohms law, stating i=v/z, where z is the impedance of the circuit. But remember that current is the measure of flow of free electrons, suppose that the conductor of the source doesnt have enough free electrons to form the current that is required by the circuit according to the ohms law..... then the voltage at the source will appear to drop. This is the worst case of loading effect. Loading is the change in supply voltage levels when a load is connected to the supply (source) output. This occurs because if no load is connected, the impedance between the source terminals appears to be infinite,hence maximum voltage is dropped at the terminals.When a load of finite impedance is applied, comparable to the internal impedance of the supply the circuit results in a voltage divider network, showing less voltage across the load than that which was measured at no load condition.
So a circuit with low O/P imped will load its output less ? Is there any other way that loading can be avoided ??