A few weeks ago I bought the Rumble 500 and I am quite close to returning it. I just can't get comfortable with it. It has some pros: Great volume. Very Great Great bottom. Awesome, maybe too awesome. Great portability. However I just can't get it to "enunciate". I can't get the clarity I sometime want without pretty extreme tone settings. I really want to control Bass/Treble as much as possible from my basses. And, I'm finding the overdrive section not to my taste. The master volume is noisy. Can I live with the Rumble? Absolutely but I'm buying new and want high bang for buck ratio. I do business with Sweetwater and the Combo field under 600 is pretty narrow. Any of you use the GK or Ampeg? Or something I'm missing. Pros and cons would be much appreciated. I currently play Rock, Country and Western using primarily a PBass.