I am a tube newbie and need some help. Only one component in my system has tubes--my Lite DAC 60 (purchased from GR Research w/mods). I've had it for about 3 years, and it is on for several hours a day. I recently noticed that my system sounded thin and out of balance. Both channels still have sound, but one has much lower volume and lots of hiss. I did an A/B comparison of the DAC and my receiver's on-board DAC, and it was obvious that the problem is coming from my DAC.
I switched out all the cables, but the problem persists. Then I pulled the tubes and reversed them. Low and behold, the problem is still there, but now in the other channel. So, I know it is the DAC, and I know that the problem is with one of the tubes.
Here's the questions:
1. Does this description sound like one of the tubes is dead?
2. When a tube goes bad, will the sound stop, or degrade over time? Will the tube still glow?
3. How do I figure out what tubes I need to replace my old ones?
Thanks for the help.