It took a while for this to sink in, but it's a very useful bit of information if you've got a PX4B, and it's NOT in the manual: Each preset is not just an effect setup. It's an effect setup PLUS an amp model. I didn't realize this because there's a separate amp model selector control, which to me suggested that the choice of amp model was separate from the choice of effect preset. I thought that if the amp modeler was set to VALVE, say, that whaever preset I picked would use that amp model. Simple, right? NOT SO. They're intimately tied together. If you pick a preset, it doesn't matter where the amp selector is pointing...you get the amp model associated with that preset. In other words, if you pick a preset, say, DISTORT, you'll get whatever amp model was programmed in as part of the DISTORT program (like "UK" or whatever it is). If you want a different amp model (say, "VALVE"), you have to choose it manually using the amp model selector. This is true EVEN IF THE SELECTOR IS ALREADY POINTING TO THE AMP MODEL YOU WANT. If you pick your desired amp model and THEN pick the preset, it won't work...choosing a preset gives you the amp model associated with the preset whether you want it or not. Pick the preset, THEN select the amp model. Okay, repetitive and redundant, but I hope that was at least reasonably clear. Hopefully it will help someone. ===== Wish list: - A BYPASS FOOTSWITCH, DAMMIT!! - Default to bypass instead of silence should the batteries die (DUH!) - Give us the ability to lock out the 97 presets we don't use so that we only have to scrolll through those we do use. - A locking or protected power switch so it's not so easy to switch on by accident - Get rid of the POP when the unit turns on - Bigger/clearer labels on the jacks Overall a great unit, though.