Look, just because one tubed system sounds soft does not mean that all will. Likewise, SS systems are all over the map from harsh to analog-like.
If tube design is done well, and I'm talking about power delivery, it will do everything as well and have a more liquid midrange. The highs may not go quite as high and the lows may be a bit flabby, but that is the compromise with tubes.
One of the best tubes for DAC output is the Siemens CCA grey-plate. I have a DAC with near-new ones in it. The highs are every bit as good as my SS DAC. The lows are a bit flabby though.
If you find a good design, then the only compromise with tubes is a bit of flabbiness in the bass.
If you want tight bass, then stick with SS.
Steve N.
Empirical Audio