Just got this thing in the mail today thanks to a fellow TB'er on the EB side. My first impressions are ... WOW . I cant believe how small this thing is. Its alot lighter than I thought also. My reasoning in getting one is that I really was pretty happy with my backline 600 just wanted to get a lot smaller. Well I got alot smaller and alot louder at the same time. I must say that it is a slight brighter than the usual GK sound set flat which I think is a plus. Plugged it into a MBX112 first and then a Wizzy 10. Both produced sounds that I can definitely enjoy with the Wizzy giving better clarity but with a little less lows. On my way to a gig now with the wizzy to see how it holds up, but I really don't have any doubts. Neither one of these speakers I'm using can handle the MB2-500 anywhere near noon without some farting. This thing gets LOUD. AND GOOD WARM LOUD NOT ANNOYING HONKING LOUD. Anybody else using these for upright? If so I would love to hear your experience/review. I will pop back with a review after my weekend marathon gigs.