Hello, I bought two 5998 tubes. The first one was fine but when I plugged in the second one I heard a pop in my headphones and I lost my regulated filament D.C. board. Maybe a short in the filaments of the tube? My tube checker does not have 5998's in the charts so I can't check it. I ordered parts to fix the regulator, but does the front tube(12sn7gt is the one I am using) need the filament voltage to the tube for the red led's to light up? I had the amp plugged in and on but the 12.6 volt filament regulator on the 12sn7gt was disconnected and I noticed the led's were not lit on the socket. Or is this a separate issue? All the other red led's are lit up on the speedball boards, so I think there OK. Thanks