I'm surprised he'd say that. I don't have LCD-2, but with HD650, K702, HE-400 (also planar, and more efficient than LCD2, though I believe higher impedance), it's dead silent. The only can that picks up noise (and a lot of it) is D5000, and that's all tube noise.
Are you sure it may not be your SOURCE that's picking up the hum and Lyr is just magnifying it? Did you try a different source, even an iPod on an LOD cable or something?
Are you sure it is dead silent? Put the headphone on before connect it to the lyr. Go to a dead silent room. Connect it to the lyr. Do you hear an difference? It is a very very quiet noise you only can hear when you apply on this.