The most neutral DAC I have heard is the Rockna Wavedream. The edition and signature tonally are the same. You get more detail and an even bigger soundstage with the signature vs the edition.
the thing about the Wavedream is the sound profile doesn’t really stand out in any way. It is not bright nor is it warm. The sound isn’t full but it also isn’t thin. It isn’t forward but it isn’t laid back. Etc…. It is hard to describe the sound because of this and in fairness, some folks find this a bit boring as the DAC is so exceedingly uncolored.
I have a Wavedream Signature and agree it's very neutral, but "boring" is not a word I would associate with it. It's very dynamic and punchy. Sometimes it startles me a little when I start playing music, even though I'm expecting it, there's just so much more body and drive than any DAC I've owned previously.
Before the Wavedream I had an Aqua La Voce S3 which to me was also quite neutral and perhaps a little more affordable for most than a Wavedream.