Help me figure out this 12AX7 Tube Preamp mess
Recommended configurations for the 12AX7 are below: 



Since the cathode resistor is bypassed for audio frequencies by the 100uF capacitors, gain will be set by the transconductance of the tube under the operating conditions, as shown in the above diagram. Lowering the plate resistance, especially on V2, will allow you drive a lower input impedance input. 

Below is your original circuit with your voltage measurements and calculated plate voltages shown.