I’m sure you misspoke when you referred to pi-squared. The 6.28 factor you referred to is of course correct, but that is 2 x pi, not pi-squaredYup- thanks for that. My medication is a bit too powerful today...
It adds better isolation on high frequencies between power supplies.But what do you think does it have any real effect?A choke is helpful as it can be used to help filter out the 60Hz sawtooth waveform that is part of the rectification process. They can be quite helpful in that regard, as to do it with resistors and filter caps essentially requires more filter caps and also means a bigger voltage drop in the power supply, where voltage might be at a premium. IOW you can have a fairly low voltage drop across the choke due to a low DC resistance, yet still filter out noise in the supply.
What do you think about separate power supplies between left and right channels for 300B SET amplifier? Does it do a significant difference?
Separate supplies is not a bad idea at all, although in a class A1 SET you shouldn't have a lot of noise in the supply. If you have separate supplies though, you could also have separate chassis for left and right. This would give you the ability to run shorter speaker cables, which is really helpful when working with amps with a higher output impedance such as an SET.
The trick is that when things stereo share a common power supply its possible for them to talk to each other (the term is 'crosstalk') and essentially interact unless great care is taken to deal with the power connections and ground connections correctly. Otherwise you can increase IM distortion and IM needs to always be kept as low as possible.