Based on the Stereophile measurments of the original test, I'm kind of surprised you get good results with the matchup to B&W.
www.stereophile.com/solidpoweramps/675/index9.html
They had some... difficulty... at 4 ohms, not to mention lower.
Also, Please keep in mind that the real measure of a loudspeaker's 'goodness' of load is a combination of impedance AND Phase Angle....the amount the voltage and current demands are 'out of sync' . This number is usually measured in degrees and can be expressed as a number called 'power factor'.
Large phase angle combined with low impedance is a deal breaker for many amps. I don't have the phase data for the B&Ws but if it follows there 'norm' it can get to 45->60 degrees. This is not a trivial number.
And, as a final note, Tube amps do not like certain reactive loads. I don't remember off-hand if it is Capacitive or Inductive which they don't like, but this too, makes a difference. It may make a difference if the amp is either direct coupled or running thru an autoformer, I have no information on that.
www.stereophile.com/solidpoweramps/675/index9.html
They had some... difficulty... at 4 ohms, not to mention lower.
Also, Please keep in mind that the real measure of a loudspeaker's 'goodness' of load is a combination of impedance AND Phase Angle....the amount the voltage and current demands are 'out of sync' . This number is usually measured in degrees and can be expressed as a number called 'power factor'.
Large phase angle combined with low impedance is a deal breaker for many amps. I don't have the phase data for the B&Ws but if it follows there 'norm' it can get to 45->60 degrees. This is not a trivial number.
And, as a final note, Tube amps do not like certain reactive loads. I don't remember off-hand if it is Capacitive or Inductive which they don't like, but this too, makes a difference. It may make a difference if the amp is either direct coupled or running thru an autoformer, I have no information on that.