Ultralinear and Triode. What's the difference

Triode mode is simply using the more liner part of the tubes amplification ability. The cost is about one half the power. The only reason for ultraliner is to try and get more power from the circuit. No engineer ever claimed that it was more liner (i.e. sounded better)
The most likely reason that anyone would prefer an ultraliner or tetrode configuration, is that they simply need more power in the particular application.

To really hear what triode is all about. You need a tube amp that uses triode tubes! Pentode tubes that are in a circuit that gives the ability to switch from triode to ultalinear does not really let you hear what triode is all about! In these type amps, almost always the ultralinear mode will sound better than the triode because the pentode tube is in a circuit that makes compromises for the flexabilty.

Philefreak ; very informative , I was not aware of that ! Just for my info , can you list some common examples of pentode tubes and triode tubes ?
Man I love this forum !

Tvad ; the two integrated amps were used in exactly the same conditions .
If you have heard the Cary SLi-80 you will know what the Cayin sounds like . I A/B'd them and could not justify the added exspense of the Cary . I am relatively new at this but would describe that sound as traditional tube . Warm mids and rolled off at the extremes . Given that Cayin outsources their parts to the cheapest bidder , it is quite possible for one batch to have a slightly different sound than another batch due to the varying components used .
The Prima Luna , on the other hand , has much better extension especially in the high end . The lows are a little better and the mids are not nearly as warm . The P.L. also shows more detail with a greater amount of air and resolution .
I would really like to get the warm mids of the Cayin incorporated into the P.L. , kind of like the best of both worlds !
I intend to call K. Deal to see if that can be accomplished by rolling some different tubes . I don't want to loose any of the other attributes though .
I hope that this helps .

I can give just a few cause I don't know all the tubes that are out there! Pentodes- EL 34,KT 88,6550,most pin guided sockets are pentodes or tetrodes. Triodes- 2A3,300B,45,PX 25,845,6C33,6AS7,etc. some of these have a 4 pin socket. My favorite amp is a Push/Pull 2A3 triode using 6SN7 as an input and driver tube. It's only 18 watts but, on my 91DB flat 4 ohm speakers it's plenty!