Separate volume controls for left & right channels

hi, I am curious to know why some pre-amps have separate volume controls for the two channels. Don't we want to have the same level of control on the channels? Can someone explain this to a novice? :) Thanks!
Much more flexability,I would think..Not all rooms are the same..Not all of us hear the same.. Buy using to seperate Left and right Mono Volume controls ( good ones ) you can control the room,ears or whatever,with out having to use a Balance control.I am actually considering doing it with Khozmo's left and right monos.......Makes great sense to me......
My Audible Illusions Modulus 3 and 3A both have dual volume controls. It may take a bit getting used to, but IMHO there is nothing like it for the flexibility and pureness of the sound. It is better than a balance control which I think degrades the sound.
From a purist standpoint it is better to have dual volume controls than a balance control in the signal path.
I had a preamp with dual volume controls once and it drove me nuts making the two channels match. Not that I was unable to do it, just that I always had the nagging feeling that I didn't have it right. A little bit of psychology and audio nervosa in play there. While it's true that there's more flexibility, the process of adjustment, listening, further adjustment every time I sat down to listen is not tenable to my expectations of instant audio gratification lifestyle.

If the dual volume controls are stepped attenuators then I'm ok, but a smooth continuous knob made me batty.
One of the advantages is better channel separation, or if you want to control right/left without a balance control.
In theory they are better, in practice I agree with Wilsynet; I had one and it drove me crazy.
Thank you for your answers, now it makes sense. Cheers
+1 Wilsynet and Stanwal. I dreaded mine after the first month of use, now long gone. I laugh when I see them now.
Some did/do it like they used to in the early stereo days where they were stacked them (volume), on the same shaft with split knob. If they had good friction it worked good, except in some cases when you turned it all the way down, one channel still had to much volume in one channel.
My linestage has dual volume controls and I love them. They`re very accurate and for me no hassle what so ever, very simple yet effective.
Has anyone found a reliable, practical system [commercial kit, Chinese from eBay, DIY from scratch, or just good-looking plans] for a mechanically linked dual VC, with the possibility of using really top shelf potentiometers, a dual shunt VC, or ideally, switched discrete resistor attenuators? You know, something with a belt connection, some kind of clutch, chain drive (!)... whatever. I'm not really thinking about some rare commercial product, but something along DIY lines. Thanks.
I had them on my Audioprism Mantissa preamp, but they were stepped and clearly no problem at all for me.

I liked the option on that preamp because I could turn one speaker off when doing testing.....and I did use them as a balance control when one of my ears would plug up a bit (every short spurts).

Seakayaker, here's a picture of the Ayre K1.
Excellent idea. Should be standard on high end equipment.