After the flurry of posts regarding the SS3601 from Sparkos Labs, I placed an order. They arrived last night and the installation was a breeze. Removing the stock LME49710 resulted in some bent pins, but i was able to straighten them out. However, I won't be going back due the fact that the SS3601s sound so much better.
Up to this point, I was completely happy with my X7. It was a huge improvement in SQ over my mixamp/m-stage combo that I'd used before, but the SS3601's remove a veil that I didn't know existed. Now the sound is crystal clear, full and the separation is improved.
I will stress what Yethal posted earlier, but take care when removing and installing the op amps. The stock LME49710 op amps are very flimsy and sit more or less flush with the connection, so removal was tough. Ended up bending a lot of the pins on the left op amp that is positioned close to the plastic casing of the X7. Like I said earlier, I gently bent them back in place, but just a word of caution.
Same goes for the SS3601s. It will be a very, very tight fit on the left side, and the silicon chip will literally hug the side of the X7 casework. This means that it will be difficult to remove. I attempted to remove the SS3601s last night, just to A-B with the old LME49710s, and ended up with a MINOR bend of a pin or two on the SS3601 on the left. I was able to gently straighten it out, but be careful.
I assume a minor recorrection of a bent pin won't affect performance of the op-amp...anyone able to comment on that? They're still pumping out amazing sound, at least.