Hi Tones and all.
I did a lot of work on this some years ago.
The difference is very marked and in my opinion, torque (more the better) and vibration (less the better) have a greater effect than stable speed (unless you are blessed/cursed with pitch perfect hearing).
I am not surprised that the WN power supply sounded similar to a Valhalla (or Basik) as the limiting factor is the simple phase shift circuit. If you measure the voltage at each of the 2 motor windings, you will find the one connected through the capacitor has about a 20% higher voltage than the other one due to loading effect of the motor. The result is significant extra vibration which has the effect of significantly muddying the sound.
I used to sell a commercial product (Norton AirPower) which used a similar 'Basik' circuit but set the voltage for each motor winding individually by the use of a transformer with separate outputs for each motor winding.
WN were once going to make me a kit using 2 separate oscillators/amps/transformers which would, I think be the ultimate way to drive an ac motor (my design was still susceptable to mains variations and could not offer 45rpm). Unfortunately, Dave was too busy to put in the design time and my need went away before he was able to deliver, but he quoted about £450 and I would sincerely recommend this route.
The Lingo also uses this formula and succeeds very well in reducing motor vibration and improving clarity but at the sme time, there is a perceived thinning of tone and loss of weight. I think this is becuase they set the voltages too low.
If anyone is interested in building a DIY version of my power supply, there is information on my website
http://www.norton-tech.co.uk
