Neutrality is important for me too. Two of the very best preamps for a neutral sound are (I also own both):
- Benchmark LA4/HPA4 (consider the HPA4)
- Holo Audio Serene
There is a review online comparing the 2 preamps. The reviewer preferred the warmer Serene I prefer the BM preamps. Both are great.
I have tried a few DACs, costing $700 - $15000. I have now come to a happy result with the Schitt Yggi+ OG (neutral) and the Yggi+ LIM (warm-ish).
I called up Schitt and spoke to a musician that was working there to discuss DACs. He hated the LIM because it was a warm and limited on the top end. One reason a lot of people like it, but as a musician he said he hated it. He then told me that the best DAC he had ever hear was the Schitt Yggi+ OG. He told me to buy the last one ever made and I would not be sorry. He was right, though it took a month of heavy playing to really break-in. The replacement for the OG is called the Yggi+ More is Better (MIB). It is supposed to be close to the OG sound and not the LIM sound.
Both the preamp and DAC suggestion will be around $6k new though on the used market the cost should be around $4k.
BTW - I can only vouch for the latest Yggi+| DACs. They have been around for 10 years, but their modular design is upgradeable. So, in the used market they maybe older units. Schitt and Benchmark support home trials.
BTW2 - I said consider the HPA4 over the LA4 because I plan to use my HPA4 with maybe the world best headphone at any price. I heard this headphone with my Serene preamp/headphone amp and it was an immediate desire to buy it. The HPA4 will be even better as a headphone amp.