If you had to choose: tube amp or tube pre-amp?

It depends on your speaker. If your speaker is compatible with tubes I`d go tube power amplifier if your goal is tube sonic attributes. The tube preamp won`t have the same influence and the SS amp presence will be known(ok if that`s what you want).
Regards,

Al,good advice, correct the root of the problem then address the lesser issues afterward.

Solid state amps won`t always result is better bass quality. It absolutely depends on the speaker design and parameters.Some speakers are meant to be used with tube amplifiers and will sound better with them(the converse is also true). It all depends on the specific objectives.
Regards,

A good tube preamp would certainly be an improvement, but your original question was an either /or tube pre-power amp.

Grannyring,
Yes life is very simple and enjoyable with SET amps.One output,driver and rectifier tube per monoblck, that`s it.
Regards,

As to which type of amplifier SS or tube will sound more dynamic is completely dependent on the speaker they`re matched with (this can`t be emphasized enough).Same is true for bass performance.Based on the designer`s intent some speakers need more or less damping factor from the power amplifier(output impedance level,yes or no NFB levels), also depends on the speaker`s Q factor.Generalizations don`t hold up, you must account for the numerous parameters involved.
Regards,