Does the volume control effect sound quality?

I believe that the volume potentiometer (pot) is the single most important component that can have detrmental effect on sound quality, this is why they all sound different to each other.
All volume controls have pin point touch contact that are purposely made light in pressure as not to wear out the resistive track or contact points, all the music signal has to try to pass through these contacts.
These contacts/track are also mostly made dissimilar elements/metals which can have a "diode effect" which tries to rectify the ac music signal, this is a form of distortion.
In order what I believe is the best type of volume controls.
1: Lightspeed (ldr based) Attenuator or TVC (transformer based) = no contacts in the siganl path.
2: Mercury Wetted Relays = with gold or silver contacts in a mercury bath, they also resist tranishing /arcing, also are becoming illegal.
3: Good quality relays = with gold or silver contacts
4: Switched resistor = double leaf, each side of the wiper contact
5: Switched resistor = single leaf on one side of the wiper
6: Potentiometer (Pot) = conductive plastic track
7: Potentiometer (Pot) = carbon track

Cheers George

After two glasses of wine, no way ;)

Atmashere, you raise an important point. I was thinking of replacing the stepped resistor attenuator (Goldpoint, 100kOhm) with an inductive volume control in my amp that uses a 12AX7 followed by 12AT7. The stepped attneuator sounds great. I want to see the sound can be improved by using an inductive (autoformer) volume control. However, the inductive volume control impedance is highly dependent on frequency. At 1 kHz it is about 1 MOhm (yes, megaOhm) and at 20 Hz about 20 kOhm. There is a 3.3 kOhm input resistor that goes to the grid of the 12AX7. Can inductive volume control significantly affect the frequency response in this case?

I know we aren't supposed to be off topic here but is the Pope Catholic?? IOW, yes.

Georgelofi, we've done a lot of experiments with controls and I find that I can't agree with your regarding relays. Universally they were inferior to a good quality rotary stepped switch. However, switches are quite variable so I can see good relays being better than some switches. But if you have higher quality switches the relays don't stand a chance.

From what I understand of light-activated devices, one would have to be quite careful in doing a substitution in the case of this preamp! The light activated devices I have seen can cover a pretty wide range of resistances- the higher values, even if a better device, will still introduce coloration that an inexpensive control of the right value wont have due to the Miller Effect issue. IOW things are getting dicy if the control is able to exceed 250K.

With experiments with volume controls go back as far as the 1970's, this is what has bought about the ldr Lightspeed Attenuator.
Almost all rotary switches have a stiff disc wiper made out of a different material to the springier metal that the leaf/leaves are made out of.The two contact points in relays are at least made out of the same material.
It is comon knowledge that two different metals that are a touch contact with current/voltage passing through them will creat a "diode effect" electrolosis or glavaic.

Herve Delartz of DartZeel backs this up as well, this is why he does not use contact volume controls either in his $25k NHB-18NS preamp but uses ldr's which have no contact.

http://www.6moons.com/audioreviews/dartzeel2/preamp.html

Quote interview with Herve:
Q: What is wrong with conventional volume controls?
A: You lose something. I use a system that varies resistance with light. However, until all the patents are in place, I would prefer not to specify the details.

Cheers George