Interesting that you are having trouble driving some Grado's. You are aware that 32 ohms is pretty low for a headphone, meaning they are easy to drive. In fact, Grado's are known as being about the "best headphone, when driving without a headphone amp".

I have a pair of SR-80's, which I am actually listening to some Larry Young with as I type this, and you probably have realized how damn good they sound!

So far I have driven them with an old Sony Discman, a Kenwood receiver, an H/K receiver, an H/K CD player, a Marantz multi-disc player, and an Antique Sound Labs vacuum tube headphone amp. The SR-80's were driven extremely well by all. Though obviously they sound quite a bit better with the H/K CD player, than the discman.

Sorry I can't help you with the speaker switch powering them (I am actually confused, does it have a headphone jack, or were you gonna splice you headphones cord to connect via the speaker +/- inputs?). I was just saying that I am surprised your receiver is having an issue with them.


*for comparison sake:

Sennheiser HD-580, HD-600, HD-650 - 600 ohms
Koss portaPro - 72 ohms
(I really like my Koss' too, but my Grado's destroy them!)