Ryan,
It's great to be back here after a hiatus and talking to you guys and seeing what everyone is doing with their I/V ideas! I've been busy building tube amps and SIT amps, so many projects in the pipeline! Anyway, those are other stories.
The I/V that I'm using is the Abbas 5687 hybrid. It loads the TDA1541 at nearly zero R with a Germanium P-P front end followed by a 5687. HV rectification is accomplished with a 6AX3. It swings about 3.5v P-P. It's a little embarrassing that I can't tell you anything more than that because I didn't draw a schematic for it, nor does Abbas provide one (and of course we would never display someones commercial work here). I simply orded it, it arrived and I installed it in my chassis and never looked back. It's a wonderful sounding I/V and the 5687 is just an incredible tube (and affordable). It's very clean and smooth sounding in my setup: It manages to be both very analog and inciteful sounding. The way your board performs with this I/V is just wonderful and it's the standard that I judge all digital audio against. The TDA1541 when done right just sounds natural: instruments have dimension to them that I've never heard from any other DAC scheme.
All of these manufacturers are doing FPGA running R2R or FPGA and I just think they simply cannot compete with this chip. Yes, they are achieving higher effective bit rates, but it hardly matters.
He's now doing this particular I/V with 5v rectifiers. Valve rectification in the HV section is one of those things that generates a lot of opinions, so, I'll just leave it at that. When I build this d3a, I'll choose one of the super quiet HV maida like Nerochromes (
https://neurochrome.com/products/21st-century-maida-regulator) or Salas HV reg. which I used for the ES9018 I/V. I alose have a Jan Didden HV boards that I need to use.
Here's Abbas' current sheet of his completed PCB offerings, and I would add that he is always open to doing other things.
https://docs.google.com/spreadsheets/d/16L4eOQPwkG-4FDVqbTBwc_FrxpRGshPEFqceI259mo0/edit?pli=1#gid=0
https://www.abbasaudio.com/en/
I just recently implemented the Audial USB to simultaneous board. I was using the JL-sounds board for a number of years and it's fine, but I do think the Audial board is slightly better and I'm getting zero pops when bit depth changes from album to album!
https://www.audialonline.com/blog/usb-interface-board-mark-3/
Unfortunately, I don't think Pedja is going to offer this board again, or at least, not any time soon. But, if theres enough interest, maybe.... The board can either be run in i2s or Simultanous mode. Of course, I'm running mine in Simultaneous.
Anyway, lot's of fun things to think about and the D3 board has created a fabulous experience!
Cheers,
Greg