with my MarkBass Vintage 500 and Blackline 250 amps, I set all controls flat. I get that pure P or Jazz tone. Of course, live I usually have to adjust,in small rooms attenuate the bass a bit usually is all I have to do.
For a laugh,and ease of loading in and out by cab at an outdoor festival,I took my Elf and one 10" cab. The sound crew laughed at first,then at soundcheck were so blown away by it that they added a mic to the DI feed. Was thunderous , from such a tiny amp.