I hadn't played much with this feature before, as it's been pounded into our heads for several years that all triode mode is superior, being more musical sounding, than any type of pentode mode (which includes ultra-linear mode). However, the music just jumped to life in this mode! Now, switching to triode mode with little or no feedback just sounds lush, not exciting. Makes me wonder why I didn't seriously pursue this option before. I guess we truly are "programed" by the common wisdom that we read, both on the net and in paper magazines. I was so convinced of the superiority of triode mode that I only briefly listened to ultra-linear mode and didn't really give it a chance before. I'm very glad I gave it a second chance.
You're exactly right. There are plenty of "gurus" who diss ultralinear operation, and their minions (most of whom couldn't identify triode, ultralinear, or pentode operation on a schematic) shout "Right on!" and give them a high five. They dismiss it as a cute parlor trick that looks good on paper but is inferior to both triode and pentode operation. I sharply digress, and have always
liked ultralinear operation.
No, it's not as creamy as triode, nor as powerful as pentode, but it never claimed to be. It's an "in-between" mode that gives you a nice blend of the characteristics of each extreme, while proportionally reducing the associated drawbacks of each. It has much lower output Z and distortion than pentode operation, and requires no screen grid power supply. Compared to triode operation, it has much higher power and is easy to drive thanks to relative freedom from Miller Effect capacitance.
One of the major things that gave ultralinear operation such a bad rap was some of the really bad vintage amps using it, that had 50 gain stages and 200 coupling caps encompassed in the global NFB loop. They have more phase shifts than the moon has went through in the past 5000 years, and as a result the sound is dead, flat, and homogenized.
But, when ultralinear operation is applied to a simple, two stage PP amp (especially one with a short global NFB loop applied back to the LTP phase inverter), or a SE amp, it can sound very good with the right speakers
. People who power their Hornshoppe Horns with the Carina universally prefer its Ultralinear Mode. Likewise, I prefer Ultralinear Mode with my little Planet 10 Fonkens, which have a similar driver.
The same thing happened in the guitar amp realm. Some of the early '70s Fenders had ultralinear output stages, in an attempt by the tin-eared CBS engineers to get lower distortion from the amp (in a day when most players WANTED distortion). They sounded so awful that they forever turned guitar players off to ultralinear operation, and (among many other things caused by CBS's mismanagement) almost caused Fender to go out of business around that time.
Today, several Dr. Z amplifiers have ultralinear output stages, including the incredible sounding Route 66 model. It'll ridiculously blow away any of the mass-produced, big name brand garbage you find in your local music store.
In the end, it's all about the music, but so many people forget that and get caught up in "audiophile politics."