Don't want to hijack the thread, but I also ordered the 681 EVO for $ 27,00 (27 !).
It is supposed to have an improved low end, tamed highs, and to be almost flat. I hope it is true cause i hate v-shaped.
I bet you will enjoy your 661 (btw, the isolation is great, it comes with 2 detachable cables, 1 m and 3 m, a nice chinese-like red satin bag LOL, a 6.3 adapter, a jack-lock, the fit is perfect, the building quality is great and the industrial look is superb, the whole package is incredible for the price)