I have looked through all the pages of the Spider Valve thread.  I am mainly interested in the issue involving the HD100 head intermitently losing power or volume.  I've had my HD100 for about a year and a half now, and recently had the power tubes replaced by an authorized Line6 tech.  At that time, the tech informed me that one of the tubes had been running hotter than the others, and although the life of the factory installed tubes were at about 50% (in his opinion), he felt it a good time to replace them.  I had him put two matched pairs of Sovteks in it, and bias them.  He said he also checked solder points, and gave it a general cleaning.  It sounded fantastic when I got it back from the shop.  Just last night after about a four hour rehearsal, I noticed the power failure.  Only lasted about a second or two.  Once the power was regained, the problem didn't re-occur.  I'm hoping that it was a one time incident, but I'll have to keep an eye on it.

My question(s), "What is the verdict on the head dropping power like that?  What's causing it?  Is it a software issue, or is it hardware?"  I just ordered another head since they went on sale at the ridiculously low price of $450.  I hope I didn't make a mistake by purchasing something with reliability problems.