Tube Watts vs. Solid State Watts - Any credence?

Music requires very little average power, unless one listens to sine waves. It is possible that two of 50W amplifiers can be designed with very different headrooms. One might have small headroom being, for instance class A amp while the oder has huge headroom with average power limited only by size of power supply and heatsinks. Amp with higher headroom might appear much louder without distortion.

14dB is rather shallow feedback.

Damping factor of 14 is OK. 8ohm speaker's impedance is mostly resistive. Assuming, that it is approx 6 ohm it limits effective DF to 1.33 . Amps DF of 14 will make it worse only by 9.5% - irrelevant.

There is a lot of local NFB in almost every amp. Any resistance in cathode is a form of NFB. Global NFB doesn't have to create TIM if it is applied within certain limits. It improves pretty much everything - bandwidth, output impedance, THD & IMD. Great sounding amp with small amount of NFB requires great design and quality components. Unfortunately it is cheaper to achieve the same using cheaper design and excessive amount of NFB hence creating overshoots (odd harmonics in frequency domain) and unpleasant bright sound.

So sorry goodbye .

10-10-15: Czarivey
"tube amps have no bass hence it's power mostly applied towards mids and highs while the solid state amps go full range."

You couldn't be more mistaken! In fact, some tube amplifiers are known for their excellent LF response.

Completely agree with everyone about the bass - if you get the right tubes, bass is certainly never lacking. Actually, with tubes, you have more flexibility to tailor it to your tastes. Certainly more tubes with have different sonic characteristics but if you want bass, I would not suggest shying away from bass. It's all preference at the end of the day.

I think bass response with either tubes or ss, might depend more on how the speakers used with them handle damping. With that said; in my experience, dynamic speakers with lower impedance numbers mated with ss amps that can double down typically have superior bass response.