Tube Watts vs. Solid State Watts - Any credence?

Thanks Bombaywalla ... but what is the purpose of partial cathode coupling. Is it a form of local negative feedback?? Does it ameliorate some of the adverse affects associated with NFB that Ralph has written about, e.g., TIM distortion that raises the level of odd ordered harmonics??

ARC has used this type of topology for many years.

Czarivey ... I think your post slaps quite a bit of paint with a very wide brush.

My ARC Ref 150 SE has a relatively low output impedance, resulting in a damping factor of 14 (assumes an 8 ohm load; would be half if the load is 4 ohms). That ain't bad for the bass. In addition, it has a 1040 joule power supply, which helps the amp to muscle its way through demanding loads where serious current (and correlatively power) is needed.

And based on my own ears, I do not concur that my tube amp "has no bass" or that its power is "mostly applied toward mids and highs." I surmise that Ralph (Atmasphere) would take similar exception about his highly regarded amps.

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.