How do tube Watts compare to SS Watts?

1 SS watt = 2+ tube watts in my experience in terms of filling a space with sound.

I have some experience with Thiel loudspeakers - mainly with Cs 2.4. I believe that the idea to drive Thiels with tube amp is generally very bad idea. Very, very bad idea. Thiels are well known as very power hungry speakers, which provide the quality of reproduction that they are known for only when they are connected to the amp with powerful output stage. You might look at something like BAT VK-150 or similar but generally you should go for SS - and very poweful SS ...

The sound level that can be produced by a tiny amount of power was made clear to me when my son hooked up a KLH5 low efficiency speaker to his clock radio. The KLH5 was a sealed 3-way system, and the clock radio was probably good for 500 milliwatts. I told him it wouldn't work, but it did, and surprisingly well.

In my experience tubes and Thiels are a very good match you just need enough tube power to drive them and there are many factors that determine power requirements. Thiels are a demanding load but not difficult one because of the relatively low but flat impedence curve.

Chuck

Depends on the tube. SET amps with 300B, 845 are low power, "no slam" "no authority", but a midrange and highs to die for, WITH THE RIGHT SPEAKER. So scratch those off my list. ...KT88's. I heard one cheap chinese 88 and also rolled 88's in my JOR. Absoluetly no authority. Very very weak on any speaker with 90db or lower. I havea Jadis DEFY sitting on my floor waiting for a preamp, has the 6550 tube. Very very nice looking tube and should be an improvement over my KT90 Jadis OR. The seller told me has "magic". Then there is the EL34, which doesn't look too interesting. Looks like a cheap KT90. There are other SET tubes like the 2A3 (ck name?), same issues as the 300 and 845. There are a few other tubes, but these are the most used in designs. Comes down to speaker first, then amp. So only the "beefy" KT90 does the job. I'm expecting the 6550 to come through as well. These are push/pull tubes. Sorry ss amps are not "my cup of tea". None.