Does the volume control effect sound quality?

I don't think anyone on this thread has denied that the volume control makes a difference. However there are engineering principles in play and they are such that if ignored, the result could be that a $4.00 volume control from Radio Shack can sound better than the best light-activated volume control system available.

There are plenty of other situations where that is likely not the case. IOW this cannot be taken out of context- the parameters of the surrounding circuits cannot be ignored. So if a light activated device is to be used, it would have to be one that is designed for the circuit.

Here is a good article for those who are interested to see how much their active preamp or passive volume control, is adding colourations/distortions to their sound.
It's called the "Ravel's Bolero Test" and you need a CD or LP of it or like it to conduct the test.
http://www.high-endaudio.com/RC-Linestages.html click on Bolero Test, scroll down to "CD Player?" if you have a cd player

It is basically doing what I suggest you do 2 posts back

Cheers George

That website is terrible!

Are you saying Arthur's opinions are terrible or his website is not user friendly?

Atmasphere, I was trying to understand your post and if I read you correctly, are you saying that the circuit has to be engineered to accept and maximize sound quality for any particular type of volume pot?

There are some audio engineers that think a good standard volume pot will outperform many of the other more expensive designs. Croft is one of them.