Tubes are not necessarily inferior to solid state, but there are few good tube designs out there. Tubes distort in a way that sounds more pleasant and every amp has distortion. (typically, crossover distortion in an A/B switching amplifier is the major key to avoid but specs don't usually show that)
For a headphone dac/amp, this should be just fine...it will likely not be quite as accurate as the O2 because the engineering behind it is what made that amp special. The Aune T1 will fair quite well vs most other offerings in this price range, though. Bad recordings generally sound better in tube equipment.
The superior amp is the O2, in short, but that doesn't mean this can't have a pleasing sound, look pretty neat, and be a unique change of pace in your collection.