Hello, I have an Essence STX which has output impedance of ~10 ohms, I'm thinking about buying a pair of Grado SR80is, which are 32-ohm. Will they perform well or should I also buy a low impedance amp? I've been thinking about FiiO E5. If I buy it, can I just plug it in the STX's headphone out? I know they should go in the line out, but I already have speakers there and I'd rather go with headphone out. Are there any downsides to doing this? Thanks for reading and cheers.