One caveat for me on the D-1. I really like the D-1 with Class A amps. A tube amp had an issue for me, the $7k RAAL Requisite VM-1a with the D-1. I sold it because it was a bit fatiguing with the D-1 and replaced it with a used $400 Schiit Aegir v1 amp (Class A 20 watts) + imersiv D-1. This was great.
I should also mention that John La Gou of imersiv is about to release a new switch using transformers with dual XLR and RCA inputs and outputs. Something Danny was also going to build but pivoted to do another project. The idea is that you could use 1 imseriv D-1 for multiple amps.
That unit would allow me to run my office, Livingroom, and RAAL Requisite SR1a headphone setup with a single imersiv D-1 DAC. Now I was planning on buying this unit from Danny (now John) but I am not going to since the D-1 cannot do DoP over SPDIF. The MA3i can and it sounds almost as good.

