Hello, I was wondering if you could help me figure out what the safe amp settings are for keeping an underrated cab in good working order. I'd like to get an Ampeg PF-800, one flip-top 15" cab, and one 15" LF cab (the non-flipping one). However, I'd like to be able to play the amp through just the flip-top cab on many occasions. I know that the head becomes 400W when running through the single cab. I know the cab is rated at 450W. I also know that this combination won't allow me to use the full power of the amp without damaging the cab and/or experiencing unwanted distortion. I don't need to use the full power of the amp with a single cab, however, it would be nice to be able to know the concrete limits of the single cab. My questions are: 1) Can it be calculated exactly what amp settings are safe for the cab, or is it just a trial by ear and common sense judgment? 2) Is the power output of the amp controlled solely by the master volume setting, or is it a combination of gain and master volume settings? 3) I assume that the gain and master controls are not linearly tapered (such that 50% on the knobs = 50% of the max). Is this true? The reason I want the 800 as opposed to the 500 is because I want an amp with a whole bunch of headroom. I've spent 20 years playing nothing but my B100R, which sounds perfect tonally, when volume is not part of the equation...but has inadequate headroom for many situations. Moving from a 100W 15" setup to 250W (the PF-500 through a single 15") doesn't sound like a big increase in headroom to me. Going from 100W to 400W is not gigantic either, but 4x the power seems like it might be an at least somewhat sizable headroom increase. Thank you in advance.