I wonder - on the Ceriatone Overtone amps, when PAB is engaged, is the entire tone stack bypassed? (i.e. all three - Bass, Mid and Treble?). 

I have a Ceriatone OTS Mini and a Volt (Made in UK) Dumble clone. On the Volt, when I engage PAB, the Mid control is still in circuit.  Apparently, the PAB disconnects part of the bass and treble controls and leaves the mid control in circuit, since the bass and treble controls have the biggest loading on the level.

Expert opinions deeply appreciated.