Pubul57 and Phaelon, my comments about 4 ohms has little to do with the tube amp in question. 4 ohm taps on output transformers in general have less performance than the higher impedance taps, regardless of the size of the output transformer. Its *easy* to demonstrate!
IOW a simple way to get a speaker to appear to be more transparent is to keep the impedance high. The speaker won't sound any different, but the tube amp driving it (regardless of the amp) certainly will.
If you could switch a speaker from 4 ohms to 16 ohms and keep all the other variables equal, the result is that the tube amplifier will make less distortion, have more bandwidth and exhibit slightly more power. Right now the only way to demonstrate that is by using a set of ZEROs to accomplish the conversion from a 4 ohm speaker to 16. But if the speaker were 16 to start with, things would be even better.
Over the holiday weekend, I found out that at least one major manufacturer of transistor amplifiers also found out that higher impedances helps transistors sound better too- not because of limited current availability, but due to the aspects of the way the transistors work in the first place.
He used a set of ZEROs to discover this.
The evidence suggests that there is not really a good argument for 4 ohms regardless of tube or transistor, although the reasons are different depending on the amplifier.
