Some time ago I used to work on music amps including AC30's. I am currently working on several and did not notice the difference in the available power output when using the front and rear inputs for any of the input types.
For example the Front top boost socket is quieter than the rear one. One of the users pointed this out to me.
I have looked on this forum for information on this - to no avail at this time.
So in analyzing schematics (many of which are hard to read) and actually measuring the manner in which the input sockets react - I have come up with an explanation.
Seems that when using either socket individually there is input attenuation to the first amp stage by the input resistors/socket-switches - with the rear socket being reduced by approx 5% whilst the front socket is reduced by 50%.
When using two guitars the volume setting on the guitar plugged into the Rear Socket will affect the volume of the other guitar.
Further research on the internet - I have found one schematic that actually indicates this situation.
This could be a nightmare - for example adjusting the volume on one guitar will affect the other.
Does anyone know why the amps have been designed in this way?