I have an original Glow Audio One tube amp, and as far as I know it has the original Chinese tubes. I think this amp was built around 2009/2010. I bought the amp used off Craigslist, and I've put probably 1000+ listening hours into. Lately, the left channel gets the odd crackles and pops. I've also noticed that the 2 smaller tubes are starting to glow blue at the bottom. I've read that this means air is inside the tube? I've attached a picture. I'm not completely worried, as I should have a WA7 coming in the mail tomorrow, but if it is the tubes giving out I would like to replace them and maybe use this amp at work. Thanks! How do I embed images? http://imgur.com/wDfyYKG Edit: I just found out that this amp does have blue LED lights under each tube. However, I'm not sure how many hours are on the tubes. I may just look for some cheap replacements.