Packing features like a built-in compressor with dedicated controls, ultra hi/lo boost buttons, midrange controls with a five-position frequency selector, and pre and post EQ control, the Ampeg PF-500 Portaflex 500W Bass Amp Head offers a dizzying array of features in one of the most compact heads on the market. A tiny titan, the MOSFET preamp and Class D power section in this model push up to 500 watts of solid state power for possibly the most powerful 11 lbs of bass-centric amplification on the market.