I think FOTM is rampant in these here parts, and this is a good example. The X1, for a while, was the best thing since Mother's Milk, and there are still some (look at the Discovery Thread) that swear by them. Now, from the descriptions, they are just "OK". I have the Q701 and the X1 (or I did, until my 16 year old daughter "liberated" the X1...), they are apples and oranges in sound. Q701 is lean/mean, some feel the bass is deficient (I find it OK). The K7xx, from what I understand (reading Head Fi), is either no upgrade from the 701,,or a relatively small one. The X1's are very comfortable (701 isn't bad). I believe there was some improvement that went into the X2-I suspect it is not day and night over the X1, but I haven't heard it, I could certainly be wrong here. It does sometimes help to give it some time to see how the dust settles; the "latest and greatest" new or upgraded model tends to get gushed over initially, then becomes old news, who could possibly want it now when "ABC" has just come out. Me, I'm the Audiophile Cheapskate-I'm happy when a new model comes out that is 5% better and costs 50% more, since it means I likely can get the now "lesser" old model at 50% or more OFF!
Just sayin'