Regarding the microphonics of the DHTs, I also have had considerable "challenges". The most important factor, I've found, is the sensitivity of the amplifier. With very high sensitivity amps, such as my ASL Hurricanes, the microphonics are very noticable. Yes- I can also hear my voice when speaking in the room near the preamp and no music playing. I've experimented with the PX-4s, 45s and 300Bs. I've found that the 300Bs (especially the WE)are the least sensitive to microphonics; the PX-4s and 45s the most. With a lower sensitivity amp (or placing attenuators in the line between the pre and amp), it's less noticable or goes away. Having said all this, if you can listen past the microphonics, I've found that the incredible dynamic range, musicality, transparancy and openness of the DHTs are worth the trouble. I am currently using EML 45s in my Grange. I have a Cortese modified to Grange currently for sale on Audiogon that changed out the DHTs for single triodes to offer less microphonics.