If by neutral you mean something that leaves the smallest footprint on the signal and simply passes it through, I'd check out the Darwin Silver ICs. For what I can tell in my system, it removed a kind of haze that I didn't know I had and everything became more coherent. I couldn't detect any coloration, fattening or leaning out of the sound, no editorializing either.
The Darwins have allowed me to use them as a bar of sorts to help me evaluate the efficacy of some older speaker cables I had laying around (which I have now gone back to) and a Blue Circle PLC. Trying older ICs didn't end up with the same degree of improvement so I truly feel the Darwin ICs are that good (neutral).
Good luck in your quest and all the best,
Nonoise
The Darwins have allowed me to use them as a bar of sorts to help me evaluate the efficacy of some older speaker cables I had laying around (which I have now gone back to) and a Blue Circle PLC. Trying older ICs didn't end up with the same degree of improvement so I truly feel the Darwin ICs are that good (neutral).
Good luck in your quest and all the best,
Nonoise