I'm putting up my Thunderfunk 550B up for sale- The amp is one of the latter models as it has the gray writing. It's in perfect condition. Great tone! $675 Shipped (USA). No Trades Please. Amp comes with like new SKB case TFB#759 Below are specs: 550-watts RMS into 4 Ohms "The Switch" with indicator LEDs Mute Switch with indicator LED Limiter (Compressor) SS/Tube Button (red) Aural Enhancer 4-Band Parametric Equalizer Timbre Control Headphone Jack Line In Tuner out Pre-EQ Balanced DI Output Post-EQ Balanced Output w/Level Control Ground Lift Switch for both XLR's AC Signal Coupled to Reduce Input Pops Pre-EQ Effects Loop Post-EQ Effects Loop Jacks by Switchcraft and ADC (of Minnesota) 2-1/4" speaker outputs 2-Speakon speaker outputs +1/-1 Aluminum Chassis Weighs only 17 pounds. Quiet AC Power Switching 100/120/220/240v operation Quiet and reliable Runs with or without the Fan