Falis,
I'm really sorry your headphone jack issue is more complicated than mine, the .5 rubber O-ring solved it fully with all the headphones I've used that have the problem. Some don't, some do. Don't want to make you mad, but can you try different sized O-rings? My headphones work perfectly without issue with the right one (.5 for mine, on several different cans). I've had no issues since then, and there is no problem with the jack seating poorly or the plugs getting loose, even with the O-rings attached.
As Patrick I guess told you, these guys have tons of experience with the Amp One and it's where Glow sends their warranty work:
hrsrecords.com - History of Recorded Sound
8517 Washington Blvd., Culver City, California 90232 U.S.A.
Phone/Fax (310) 204-4911
I've been dealing with Len over there, (len@hrsrecords.com) and he's been awesome. But yes, it costs money, which is why I did not send it in. Again, I solved my problem with the headphone jack using the simple O-ring for all my headphones that didn't fit right (some do), and it made no sense to spend money to fix what essentially worked fine with a cheap fix. Sorry yours seems more complicated than that.
I've never personally had any issues with Glow getting back to me via email, or Patrick being uninterested in any way, though it can take several days for him to get back as he is a full-time working professional who travels back and forth to China doing quality control, and thus is not always available to answer immediately. But he always gets back to me, and takes a lot of time to write very comprehensive emails openly explaining their problems and solutions in full, and providing lots of helpful info and advice. I bought my amp direct from Glow for that reason, and they've never let me down.
The reason I went with Glow instead of Woo, which was my original first choice, is because whenever I wrote Woo I got a short email response if any - many times I got none at all. I may be mistaken, but I got the impression that it was a kind of elite company that has enough business that it doesn't have to worry about its small customers. That may or may not be true, but what I do know is that I wanted a company that would be willing to work with me personally, and help me get the most out of what, for me, was a pretty large investment. It turned out well, as I feel that I know Patrick and he's always available to help me get the most out of my Glow and is always looking out for my best interests with the product.
Also, for other thread posters, by attaching a homemade cable from another Head-Fier that bumps my 65-ohm K701 to 295-ohm (155 as previously listed), I have zero hum whatsoever at all volumes. Glow does specify 300-ohm minimum for best results.
As for the DAC, I never use it, but that info you posted on your other thread, Falis, is good to know.
Hope that helps, d.