@james633 I am a Thiel CS3.7 guy now and maybe I can offer some Benchmark feedback. The Benchmark HPA4 preamp is great. It will make any DAC sound better because it is quieter than all DACs connected to it and the volume control is of very high quality.
I also have the Benchmark DAC3B it is pretty good, especially when paired with the HPA4 with balanced cables. However, I have a new DAC that I find a lot better than the DAC3B and I use it with the HPA4. It is also cheaper ($1500) and I believe it measure just as well as the DAC3B. It is the Gustard X26 Pro.
The One to Beat: Gustard X26 PRO DAC Review (soundnews.net)
I use the Gustard with 2 preamps using RCA and XLR to each one. The CODA 07x, a warm preamp, and the HPA4. Both going into a Class D amp for my Thiel CS3.7. I have 2 sets of long XLRs from each preamp. I have the DAC3B setup the same way with RCA and XLR and can easily do comparisons. The Gustard is the clear winner. It is a bit warmer than the DAC3B and really detailed with a very big sound.
I should note that I had an issue with the first Gustard X26 Pro I bought. It was on rare occasions outputting increasing noise after many hours of playing. I would power down for 10 seconds and everything was good again. I have a contact in Texas who bought the Gustard X26 Pro after me. He did not have this issue. So I contacted the Chinese seller and they told me to send it back. I sent it back by USPS for $116 and they sent a new unit in 7 days. The new unit does not seem to have this issue.
I also used it as a preamp but the 2 preamps I have are much better.