I bought the Little Dot Mk2 for my Grado 225s, and up until now, haven't really had any other headphones that need more power. I found I could get by fine just plugging the Grado's into my Presonus usb audio interface.

Sometime between then and now, I got a Magni 3, which has been useful for routing my subwoofer to receive signal only when the headphones arent plugged in.

I've toyed with the idea of upgrading to the Magnius for its balanced ins and outs, but I don't need its extra power or size at this point, so it looks like the Magni 3 will be my headphone amp for the time being.