Regarding the Furutech NCF wall plate, I did find it to have a rather large effect in my system. More than I expected. And I've had similar great improvements first from going to all GTX(R) outlets, and then upgrading them all again to the NCF outlets. Thought there wouldn't be that much more improvement to be had.
However, I would say that in my system the wall plate wasn't completely neutral to timbre. I got greatly enhanced microdetails and air, but a lighter overall timbre, not as meaty of a tone, and the soundstage depth increased a lot, but took away from that sense that the performance is right there in the room. Greater depth into the recording, but that recording was no longer in the room with me. YMMV.
I kept the wall plate because I think I was hearing more clearly into the recording, and focused on preamp upgrade to address the "in the room" engagement factor. But once in a while I do wonder about taking that wall plate back out of the system to see where I'm at now. It's just not easy to A/B!
However, I would say that in my system the wall plate wasn't completely neutral to timbre. I got greatly enhanced microdetails and air, but a lighter overall timbre, not as meaty of a tone, and the soundstage depth increased a lot, but took away from that sense that the performance is right there in the room. Greater depth into the recording, but that recording was no longer in the room with me. YMMV.
I kept the wall plate because I think I was hearing more clearly into the recording, and focused on preamp upgrade to address the "in the room" engagement factor. But once in a while I do wonder about taking that wall plate back out of the system to see where I'm at now. It's just not easy to A/B!