Special_TNo. A tube amp will only create more distortion, and alter the frequency response of headphones in an arbitrary fashion that may or may not address any real shortcomings of any given headphone.
Since a tube amp will alter the frequency response of a headphone, and since most headphones have an imperfect frequency response, it is possible that a tube amp will make a headphone sound better (if it happens to alter it's frequency response in a manner that improves upon it's shortcomings), but it's also possible that it will make things worse. Chances are, you'll get the latter, but you really don't know unless you take a measurement.
The best way to improve the sound of a set of headphones is to use EQ. Even better: a parametric EQ. But then you have to know what you're doing.