How do tube Watts compare to SS Watts?

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.

I had trouble driving CS2's with Quicksilver mono amps that were rated at 60 wpc. The room was about 12 x 20 and I thought I needed tubes to make the Thiel's sound smooth and sweet but when I switched to a smaller high current SS amp they were controlled, not sloppy.

Best advice I can give is try a tube amp with some guts and use the 4 ohm taps if it has them. Or get a SS that doubles into 4 ohms.

Watts are watts. Tubes sound better than SS when they clip and its more subtractive. SS just sounds crappy when they clip.

Some manufacturers of solid-state amps have taken this into account. Levinson amps, for example, have a built-in smoothing circuit that eliminate this harsh clipping sound when the signal gets close to the supply rails. Another that comes to mind is McIntosh, whose PowerGuard circuitry has received acclaim as an effective mean to end hard clipping.

As for the Watts question, in theory it shouldn't really matter if the amplifier is tube or solid-state, because strictly speaking 1 Watt = 1 Volt x 1 Amp. In practice, the specification is approximate, so you can expect an amp with a bigger power supply and lower impedance to sound louder with the Thiels. Also, all amplifiers differ in their "power margin" above its nominal power, depending on their circuitry details.

As a general rule, 100 Watts per channel would be a good starting point to choose an amp for the Thiels. If the brand is serious it will correctly specify its product, so you shouldn't find differences of more than 1 o 2 dB in acoustical output between a solid-state amp and a tube amp in this particular case.