Vin / Ri = - V(out) / Rf
Since both inputs of the opamp are at the ground potential, there are no non-linear currents charging or discharging its input capacitance. This resolves the second issue of the non-inverting configuration described in my previous post. Unfortunately, the "one ground" issue is still present; gnd1, gnd2 and gnd3 still need to be one and the same point.
Two inconveniences are introduced by the non-inverting configuration, although they do not directly degrade the amplifier's performance. First, the input impedance of the inverting configuration is equal to the value of Ri and is generally low; a typical value is in single kiloohms. This may be too low for the preamp or a volume control. Second, the source impedance adds to Ri and reduces the amplifier's gain. The catch is that the LM3886 is only stable if the gain is 10 or more. If the source impedance is high enough, or if the input is left disconnected, the gain will drop below 10, and the opamp will oscillate.
These two inconveniences can be addressed together by placing a buffer in front of the power amplifier:
