Metronomes, they have taught me so much about lead playing and i’m sure that although it is mainly to do with the amp, if you practice the lead work with the 6505+ (Great choice btw) it will help you get used to the amp and how to deal with the change in sound. I started using a metronome about a week ago, after playing for 5+ years ans i cant believe i tried learning without it. But like I say with most of my posts to help people, I don’t know what stage you are at with your playing so this is just a general suggestion.
Hope this helps dude!