in my experience, these Chinese amps usually sound really good. AND are a great bargain. If I were Audio Research or Conrad-Johnson I'd be worried.one thing, though--I've had quite a few of these things brought to me after the importer or mfr. disappeared. Usually the power transformer died, or there was heat damage due to something burning up on the PC board.
so, if you want your tube amp to last, take some free advice--KEEP IT COOL. Point a fan at it and live with the noise. The amp will last longer.