I hate to say it, but now I think maybe I like my amp in ultralinear mode versus triode

When Ralph and others talk about "optimizing" the amp for UL or triode mode, one thing they’re talking about is maintaining appropriate levels of feedback for each topology (assuming the amp uses global negative feedback). Switching from triode to UL increases the gain of the output stage. Switching the other way, from UL to triode mode, will decrease the gain. This affects the level of negative feedback the input stage will see. Let’s say an amp is optimized for UL mode. If you switch to triode mode without changing anything else in the circuit, you *decrease* the amount of feedback. I think this is often why people hear an "improvement" when switching to triode mode. You’ve reduced the amount of feedback, resulting in a sense of "clarity." The problem is, you’ve also reduced the output impedance of the amp and thus reduced the amount of control the amp will exert on the speaker. So the other comment you get is that bass sounds "looser."

Conversely, then, if an amp is optimized for triode mode, switching to UL mode will *increase* the feedback, and this may detrementally affect the stability of the amp as well as the sound.

Some "switchable" amps will include a circuit that changes the feedback network for each mode, thus "optimizing" the feedback circuit either way. Whether the Cary amp does this or not is a question for Cary.

But more to the OPs point, I have built amps both ways and have always preferred UL arrangements, sonically speaking.

For those who want to understand a bit more about these different topologies, there is an excellent article geared for the layman here:

https://oestex.com/tubes/ul.html

And if you want to better understand the issues of "optimizing" an amplifier for various modes of operation, there’s a slightly more technical but superb overview offered by Dave Gillespie over at Audiokarma:

https://audiokarma.org/forums/index.php?threads/regilding-the-gilded-lily-heaths-w-2m.767851/

Even if you stop after the short history of feedback amplifiers Dave provides, you’ll have a better grasp on how your own tube amplifiers work!

The "Gilded Lily" Dave refers to is actually the amplifier I build for myself, using a modern copy of the original Peerless output transformer. This is where, for all intents and purpose, the "ultralinear" configuration is in every way preferable to triode operation--to my ears, anyway. ;-)

I'll also add, in reference to "marketing," that IMHO a "tube-swappers dream" is definitely a marketing ploy, in that there is no way an amp like that can be truly optimized for each tube--as Ralph cogently points out.  I don't believe there's any harm being done here, but anyone with a technical understanding of tube amplifiers (and I'm barely on the periphery of that circle) will shudder at the idea of a "one-size-fits-all" amplifier. ;-)

Shudder is right.  Thank you for your excellent contributions dogeared.

@dogearedaudio , I just took a look at the specs listed in the V12 owner’s manual and under feedback it says "zero."

I do remember on another "switchable" amp I referred to, the Mesa Baron, on the back panel there were knobs to adjust feedback. I do not recall playing around with that particular adjustment during the two days that I auditioned that amp.

As far as "tube roller’s dream", I should clarify that I dredged that up from my memory (which is USUALLY pretty good) but since I cannot find the blurb for whichever amp it was, I probably should not be providing a designer/manufacturer’s quotes that I cannot find to reference back to.

@dogearedaudio "...anyone with a technical understanding of tube amplifiers (and I’m barely on the periphery of that circle) will shudder at the idea of a "one-size-fits-all" amplifier. ;-)".

To your point, while you can run different output tubes in many of DH’s creations, stemming from his former life with Cary Audio, and recent times creating Inspire, like the early years of Cary V12, V12R, or SLA-70 @immatthewj is referencing periodically - his amps were/are designed and listened to with a very particular output tube in mind. in the case of the V12/R. It’s the classic EL34 tube, paired with particular transformers and input/driver tubes that make for an interesting blend an sound.

Today, If you splurge and buy one of Dennis’ small and more recent 300B amps, you buy it with the new re-issues WE300B tubes, and you pay a bit extra for it and that’s how the designer likes it and wants it to be. Only comes with these tubes.

Falling on my own sword, my existing mono amps were designed with specific power transformers and plate voltage (650v) and such to run TungSol KT150 output tubes in their optimum operating window. With my speakers, I enjoy both sets but also really like how KT120s sound in these amps. Go figure, lol. :)