Slowhand, I have seen the Hal-o tube dampers right here on the Audiogon Classified. I think that one of the main dealers puts an ad up regularly. They also have feet and other isolation materials of the same stuff.
I think that if you play reasonably loud, the dampers are a good idea for the Syrah. The Syrah has the tubes standing up right in the open. This allows alot of airborne vibration to get to them. Vibrating tubes in a preamp is not a good thing, because any vibrational effects that happen in them is going to be re-amplified many times as the signal proceeds down the amplifiction route. The situation would be the worst in the phono section tubes, where the amplification factor may be on the order of 100,000 times before it gets to the speaker. The Hal-O tube dampers seem to be a good design, and don't melt, from what I've heard. It is also important to get non-microphonic tubes for a preamp application, for the same reasons stated above. You see, the plates in the tubes also vibrate internally, causing anomalies. When you buy your tubes, make sure that they have been checked for microphonics, and accurately represented by the seller. Andy, at Vintage Tube Services, is very good for this.
The tube dampers sometimes make the sound less "airy" because in some cases, the "airy" sound is produced by some small level microphonic effects in the tubes.
Some people also put tube dampers on the tube bakelite bases to reduce vibration there, and sometimes even use a damping treatment to the tube sockets.
If you like some of the "airy" microphonic effect, you don't have to do all of the tubes, or use only one damper per tube, depending on your particular needs.
