Hello, I had the same problem with mine 10 min after using my Condenser Neumann Mic this week. I think I did a bad thing by unplugging my mic with Phantom always on. I know this could be dramatic for some circuits but I did that several times on stage or at home with other gears (Bose L1 mod2, sound cards apogee etc …) and never never had this happened. I think the Helix mic preamp circuit is not fair and well protected, but I’m singer and not electronic “Ingenieur”… no way to put 100 / 150€ to fix this because I’m afraid to have another rapid problem . So I use an external preamp and put my vocals in a free return in my Helix, ok it’s TS jack and not XLR but it works fine… if the external preamp is a first choice I think it’s a good way to always use Helix for my vocals… musicalement Philippe