Played a live radio show last night. The event is a volunteer event where gifts for underprivileged folks are wrapped. I have played it for many years and this year we were in a new venue....and that is where the trouble starts. I arrived and the sound man for the radio station asked what I needed to get hooked up. I told him I just needed power and that he could plug in to the D.I. on my Aguilar AG 700. So he brings me power from an extension cord and I power up my amp and it is working fine until he plugs into the D.I.! Sparks...smoke..and a blown AG 700 and a blown Mackie Mixer (the radio station's mixer). Great. I went to my car and retrieved my back up head..Genz Benz Shuttle 9.2. Plug it in but then thought about that little receptacle tester in my bag...plugged in the tester and it showed the power was wired wrong! Got extension cords and ran power from a correctly wired receptacle and thought all was right. My amp powered up fine and sounded good. Then the sound guy went to plug in to the D.I. and again I see sparks fly! The Shuttle was still working but I had fears about the D.I. being damaged. Played the gig and came home and checked the Shuttle and, sure enough, the D.I. is damaged. The radio station is going to pay for the repairs but, man, I sure wish I had used that little receptacle tester before I turned on my Aguilar. This is a link to the tester. https://www.amazon.com/Electrical-Receptacle-Outlet-Ground-Tester/dp/B0012DHVQ0 Get one and use it EVERY time you go to a new venue.