DESC: 9-band graphic EQ. Variable compressor., The sound is in your head. You've played countless instruments in search of the ultimate soul mate. Now you need an amp that will speak your sound to the audience. That's where the Pro Series heads live. The majority of Ampeg Pro Series heads feature multi-tube preamps (not a single 12AX7 like many competitors), 5-position mid frequency selection, and Neutrik Speak-On¬ connectors that lock and provide better conductivity.