I have purchased Violectric V-222 amp and use RME ADI-2 as DAC, honestly the difference in sound is minimal, V-222 is slightly warmer in sound, but the quality is not better, just different, I assume the same difference applies to tube amps.
My Violectric has more power, which I honestly don't need, I don't play louder now than before just because I have more power, is it worth the difference? for me it was as I like a slightly warmer sound, but the cost is not worth it unless you have the money to spare.