I realize this is a really naive question, but I have been using a traditional amp for years and planning on pickup up an Ultra and a FRFR monitor. I have seen a number of setups on this site and my question is - what purpose does the power amp serve when utilizing a device like the Axe Fx? I have seen a number of racks on this site with power amps. Can I run the Ultra straight to a monitor/speaker, or do I need the power amp? If I do need a power amp, any suggestions? Thanks!