Nuvista Tubes - General

No. Not necessarily. It depends on everything - circuit, quality of transformers, type of tube, configuration of tube, quality of passive components. Adding tubes is not a panacea for some "tube sound."

Agreed. That's why I prefaced the question by stating "all else being equal".

@georgehifi and @viridian

Thank you both very much. A lot to read through and digest.

From what I gather from your input this far the use of nuvistors in the MF design does not necessarily in and among itself produce the famed tubed sound, and instead and more broadly where other tube amps are concerned, is dependent on the circuit in its entirety.

That’s why there’s so much rolling goes on with caps as they all have their own coloured sound, the best cap is no cap for the ultimate transparency..

Right. But frankly this is something I’d much prefer to avoid. I’m not looking to "tweak" the sound of a particular product, although I can understand the desire and benefit in doing so. Instead, I prefer to "set it and forget it". 

I see that. And I hope I wasn't patronizing! It's just that they are such different beasts. And what is a tube sound anyway? One would never believe my 1960s push-pull amps were tube if one thought tubes were warm and lush. I have had sand amps that were like that.  

I see that. And I hope I wasn’t patronizing! It’s just that they are such different beasts. And what is a tube sound anyway? ....

All good. And your question is well taken.