I was wondering if any of you have ran into this and what your response was.
I was playing a gig the other night and I had my backline set up and it was agreed since we were the headlining slot that the other two band's bassists would use my amp, it get's to sound check and my band does a sound check and then the next band gets up to do a line check and that goes through with no hitch, the final band (which opened up the show) get's on and the bassist says to me "come on stage and write down your settings so I can change it to mine" so I said "you're not touching my amp, just plug your pedal board in and line check" and he starts ranting at me and the sound guy puts him in his place so the bassist just storms out.
I have had a couple of bands say to me that they are changing the settings on my amp, it's completely wrong for someone to do that.
Any of you guys had a similar experience?
I think both of you over reacted. As you were providing the rig you should have anticipated some twiddling of knobs - at least to get the gain to match his bass/pedalboard, otherwie, as others have said you shouldn't have offered your amp for the others to use. AND he did ask, even if he did so in a slightly douchy way.
Having said all that, as the "other acts" who are using the closers' equipment, I would say that's life for the other guys, when you are the opening act you don't get the sound you want - you get the "headliner's" sound with minor adjustment. Also, since the sound-guy has set up around your band's balance it is silly of him to mess with things as it isn't likely to sound as good as the sound you are at. He (the other guy) needs to realize that when it's his turn to be the main act then he gets his own settings, until then the sound is going to be a compromise and if he doesn't like it he can (as others have said) get a good preamp and put that directly into the DI.
In the end, you have a right to let the guys know they need to be respectful of your equipment and that you won't tolerate abuse (and some guys think that blowing up amps is totally "rock and roll"), but within the realm of appropriate use, you have to expect a little knob twiddling.
Also - people get too hung up with their settings. If you can't get your amp to within 10% of "your tone" even before you've plugged in your bass, then your settings are far too elaborate and you are either using crap equipment which needs that much tweaking or the wrong equipment for your needs. In all my nearly 30 years of playing I've never had any amp that I couldn't set up within 1 minute - because everything was close to 12 o'clock - with most modern amps I leave the EQ alone and turn the "character" knob until I hear the tone I want (also usually close to 12) with conventional setups - a very slight smile (bass 1:00, mid 11:30, Treble 12:00 or 1:00). Seriously, if you can't get a slightly lifeless version of the one you want going straight from your bass to the DI, you have bad or the wrong equipment.
Back to the original point - let the guy tweak a bit, but give him the stink-eye if he goes too far in any direction.