I have really enjoyed my two dacs, which are the Merason Dac1 Mkii and the SoulNote D2. I think they both would qualify as boutique.
As with everything, I have found it’s all about synergy. The Merason Dac sounds sublime with the Gryphon 120 integrated (really special amp, btw) and the SoulNote D2 sounds spectacular with the Qualiton P200 tube amp and LTA level 2 preamp. It also sounds great (but less holographic) with AFG Audion mkiii mono blocks.
Merason is somewhat laid back, musical and cohesive. The SoulNote is more lively, energized and detailed. Highly recommend both, especially when matched with the right systems.