300B for LS3/5A?

I drive my LS3/5A's with 2A3 SET (3.5W) in a small room with very good results.
If you have a small to medium listening room,300B amp would have no problems.
Bass control and dynamics will not be comparable to a good SS amp,however you will have all the midrange magic of LS3/5A's.
As Mcfarland mentioned above,with 300B you won't be able to go very loud.
All this IMHO.

Will run them but best to match loudspeakers to amp at 11ohm great but 82db 1 watt. Your at the bottom end or far past of what a SET can drive. Might be great for nearfield but dynamic range will suffer. If your sold on the wee BBC monitors and SET look for a 845 or other higher power SET. I see many running loudspeakers that are at the xtreme of what a SET can drive most give up on SET after. Or on forum they go saying SETs distort, have no bass,can not produce much SPL etc etc. Best to SET ;0 up system right from the start. Make sure amp loudspeakers are a good match.

I have heard 300b driving the 15ohm version with very good results even in a living room! But not sure if 11 ohms would make a different?

My personal memory of LS3/5a's (20 years ago) is that they are very colored, in a beautiful way. They emphasize midrange and present it wonderfully. They are shy in the treble "air" and also they have a bump in the upper bass region to compensate for lack of lower bass.

This is kind of also a description of a 300B SET amp, or at least the typical one. Midrange emphasis with great beauty, lacking in air, great presence. Bass might be deep but lacking in control.

SO, on paper this is not a complementary match, but a match with similar biases.

BUT my own experience is that audio gear matching often achieves counter-intuitive results.

I would not have high expectations of this match but have no doubt it would be fun to try :)

And it might work well, quien sabe?

Art

best with push pull.....in many ways, still incomparible.