I was thinking about getting an aguilar DB659 preamp to run in front of my AG500 or in the effects loop to get alittle more roundness and low-mid range grunt. Also to get a slight low end boost. I have owned the 659 before and regret selling it. I figure that with this pairing, I will still have the lightweight, 2 channel setup with more of the aguilar tube sound. What do youy guys think? Anybody have one used for sale?