Impedance Select Switch?

[MichaelSmith]

Hi,

I'm designing a headphone amplifier with an OPA1622 output stage. I want it to be capable of being used with 32 ohm and 600 ohm headphones, so I figured I would put a selection switch in the feedback path allowing me to change the gain of the amp for the expected impedance. In the schematic below, this switch would break the connection between R8 and R6. Note that R7 and R10 are the two sides of a volume control pot.However, I'm beginning to wonder if this is overkill or could cause problems. It could be easier just to always use higher gain, but this would mean that the the volume pot wouldn't be able to travel the whole distance for lower impedances. I wanted to get some feedback from those more experienced than me in this area. Is this overkill? Is there a better way to implement this? Any feedback would be greatly appreciated.

Please help.

I didn't find the right soltion from the Internet.

References:
http://www.diyaudio.com/forums/headphon ... witch.html
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Thanks