I know, they never said there was a warranty, my complain is about the support: they took a week to say "nothing I can do, sorry"; no contact to the manufacturer, no contact to any repair company, no options, nothing. If they could just tell me who can I speak to in order to get a RMA (as far as I know, any CE compliant electronic product HAS to get a minimum 1-year warranty, not 100% sure about that), or at least let me know who could fix this for me.
Thanks for the details, I'll definitely try those mods out. Yeah, I had some hum initially in one channel (don't remember which one), but it went away after some burn-in (removed power tube, unplugged RCA inputs and headphones, turned on for 6-8h daily for a week or so). Stock tubes had even worse hum, NOS were better but still there. It had a dead silent background last time it worked, and it sounded great with my HD6XX (and terrible with any low impedance cans, from planars to closed back dynamics, specially planars sounded dull and congested).
Would it sound better with high-impedance headphones if I replaced the output caps? I don't care about low impedance cans too much, because I know OTL tube amps have high output impedance and there's no point trying to drive low impedance headphones from it, they won't sound "good", right?. Also I have some other amps for driving low impedance headphones, so no big deal.
Thanks for your time, I appreciate :)