So, this thread has been dead for about a month, but it is kind of an official one, and I'll revive it with an experience/review of op-amps I have recently acquired for my ZxR. They definitely deserve it.
Sparkos Lab's SS3602, they have been mentioned a few times on these forums, and when they were, people talked about their amazing performance, expensive price, and their rather hefty size. All of these are true, but they bring much better sound than many other op amps of the same price, as long as you can give them a proper shove in there.
-"Mother, do you know what THESE are?"
-"Uhh... toothpicks?"
-"These are operational amplifiers. That cost almost 80$. Made in America."
I've only used the I/V slots for SS3602's, I don't care about the buffers since I'll only use the headphone out. If you need buffers though, I've heard others recommend using SS3601's for that. Also notice that these are rather big, which produces two potential problems:
-You won't be able to fit the EMI shield back, but the EMI shield really doesn't matter that much, especially in my case since I'm pretty sure that my GPU's backplate, which sits directly below my ZxR, acts as an EMI shield of it's own. Also I've heard people say that the EMI shield can actually cause problems, probably has something to do with grounding, I don't know. And last, if you really want the EMI shield, I've also heard that it might be possible to cut holes in the EMI shield for the amps to pop out.
-This also makes the sound card take up considerable space in your actual case, in fact, it would be best if you could reserve 2x PCI slots for the card alone. If you can't, you might be able to squeeze it in there like I did, but you might cause damage to your card or whatever is blocking the card, as it will make the card sit diagonally. My system appears to be working fine though.
Now, let's talk about actual sound performance:
MUSIC: I'm definitely very satisfied with these. The amps produce a neutral signature, it doesn't favor anything, but at the same time it somehow makes everything shine. The bass is tight and punchy, which is precisely what my fanatically neutral DT880's need. The highs are absolutely brutal, in a good way, and the mids are pleasant and give great backbone to music, although I feel like they -MIGHT- be a little bit recessed. Could be wrong though. They give a greater sense of imaging and 3D space in music. Every note is detailed and has character, every harmony is layered and yet whole, and the harmonies are given a lot of depth and height (and I'm not talking about sound signature).
The main reason why I am so self-surprisingly satisfied with these is a bit more subjective topic. I'm an avid listener of avant-garde music that focuses on atmosphere more than the actual "music". Various modern forms of metal, ambient, jazz, post-rock, things like that. And in this music crispy clear highs aren't always a good thing, and bloated bass isn't always a bad thing. It's atmospheric music, it chases atmosphere, not sound quality, and sometimes it has to sacrifice sound quality to bring more atmosphere. But the thing is, these op amps don't really ruin it. It's up to the musicians and producers to decide how something is supposed to sound like, and these op amps make whatever they made shine. I know it's a word I constantly use, but I have no other way of describing it. Still though, I'm not sure if I can really call it "better", but it is different, and I think that I'm gonna stick to it, as more often than not, I do like the difference.
However if you don't listen to this type of music, then these op amps are no-brainer. At least as long as the aforementioned problems of price and size don't bother you.
GAMING/MOVIES: Well, as you have probably already gathered, to use a crude image, the bassy impact of a sword hitting flesh, and the afterward treble of the sword slicing through it, cannot sound better than with these op amps. This is especially true with my DT880's, they complement each other so well. The killer highs of the DT880's are brought to an even greater glory, and the deep but neutral bass is made punchier. Everything from explosions, bullets whizzing around, and arms clashing, to dialogues, footsteps, and wind, is in an apex of sound. I really cannot imagine them being better.
What else is there to say? They are amazing and well worth the cost.