Transmission line speakers - great with tubes

Can those with experience, explain why transmission line speakers are great with tubes? I've been using my Buggtussel Circa speakers, which are transmission line based, with both my Scott 222C and John Hogan 300B SET.

The sound is just outstanding! I thought I was going to run into trouble because the Buggtussel Circa's are 89DB sensitivity and the Scott 222C is 18watts/ch and the JH 300B is 8-10watts/ch.

The sound is so good in fact, that I've bought another pair of transmission line speakers to (possibly) replace the Buggtussel Circa's. The new (to me) speakers that I have coming are a pair of Meadowlark Swallow's. I'll post my impressions of both of these transmission line speakers.

It's fairly close to an "apples-to-apples" comparison. Both are 2-way configurations, same sensitivity (89DB), fairly close tweeter and woofer sizes, and employ high quality point-to-point crossovers.
Many ways one can design loudspeakers that are great with low power tubes. TL designs are not the only way. Just one way of getting it done. Bass in TL designs can be very good but other wise nothing else in a TL designs makes it superior to other types for SET use you just like TL and nothing at all wrong with that;)
I think it may have come across the wrong way. I'm just very surprised that the TL speakers that I used with my SET and pP tube amp worked so well together. I thought the 89DB sensitivity would cause problems. The TL speakers are definitely not as nice as when I use my Klipsch. Nevertheless, I was just sharing my surprise at how well the TL speakers worked with the SET and PP.

Sorry if it came across any other way.
If you get a chance to pick up a pair of Buggtussel Amygdala's .... grab them. The TL bass on them was one of the best I've heard.
I'm not familiar with the Circas, but Kevin Blair of Buggtussel went to great lengths in his designs to achieve an unusually smooth impedance curve. This makes more of a difference than most people realize, and is probably among the reasons the Buggtussels exceed your expectations with low-powered tubes.