Tube Watts vs. Solid State Watts - Any credence?

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.

I believe Atmasphere mentioned once particular B&W speakers consisting of lower efficiency 4 ohm bass speakers with higher efficiency 8 ohm midrange and tweeter. Speaker has great bass when amplifier doubles current on 4 ohm speaker, but not so great when driven by tube amp that doesn't do that.

@Kijanki ... thanks for your informative response. You wrote:

"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."

In my case, I drive my speakers, which have roller coaster impedance and phase angle plots, off the 4 ohm taps. To my ears, those taps sound "overall" the best. While it may result in non-optimal impedance matching at higher frequencies, I surmise that the power demands place on the amp are not that significant at such frequencies. Further, as mentioned above, the amp has a very robust power supply. Hence, I doubt that the mismatch is resulting in considerable distortion.

Kinjank, you also write that:

"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."

I surmised the same as posted above. I wrote that ARC said the use of NFB is part of an overall engineering solution that balances many variables.

Thanks again.
BIF

Wpc is wpc. I think there are other factors at work here to account for differences (as Mapman implies).