Help :( Speakers making constant static sound I cannot figure it out

Is there any visual check or device to test the age (in terms of usage, not years) of a tube to get a reasonable impression of how far along in it's useful life it actually is?  Do they flicker like an old lightbulb when they get old, or burn brighter (or not as bright)?

Besides visual inspection and putting it on a tester, I don’t know.

Visual inspection would entail a broken wire, a white powder if it lost it’s vacuum...

Incidentally, does your Rogue have auto-biasing of the power tubes?

It does not have auto-biasing, but I did test the bias on the power tubes when I had everything opened up and they all tested normally, nothing looked out of the ordinary.

Many good ways to attack the problem are presented here, the most effective in my estimation is to replace one tube at a time until the problem vanishes. Since the dual triode tube is likely providing preamplifier duty for both channels, I would start there. Moving thru the tube chain until you find the problem. If you have replaced no tubes recently, you might consider getting a couple of extra sets to keep on hand in the event you have another problem crop up later. For the price of a couple of sets of tubes, you might very well be able to find a nice solid state amplifier that would not have the maintenance issues that tube-based equipment presents. I fully realize that if you are a die hard tube fan that suggestion is laughable. Its ok, I promise not to be offended by your fondness for tube equipment if you promise not to be offended by my suggestion to go to the dark side of solid state. :)

Oh it's a perfectly reasonable suggestion.  The truth is tubes are where I started and so I've just been with them ever since, but as I've periodically traded up in the same line, starting at the original Cronus Magnum and eventually the v2 and now 3, I've managed to never actually have a tube burn out on me, so never had to really deal with much in the way of headaches/maintenance during those ~15 years.  

So I have no negative feeling personally about solid state amplification, I just haven't had a reason to feel strongly about making a change.  I've heard SS systems at dealers and shows ranging from "shrill" to "meh" to "holy crap that's the most beautiful thing I've ever heard" (though I could never afford the latter), but it would come down to something that played nicely with my existing system and general tastes.  

I promise, every time I ever move apartments and have to lug that beast by hand, I wonder about switching to some modern high-tech class d that weighs 10lbs and fits in a briefcase, but then when I curl up at night with just the light of the fireplace and the tubes glowing and hear something that sounds just a little more romantic than clinical, I forget about the inconveniences.