Are USB-SPDIF's relevant with today's DAC USB technology?

The Berkeley Audio DAC, which is one of the best, does not accept USB in. Why?  Because using a converter is currently the best-sounding option. Their converter is top notch, as well as the M2Tech when its used with the optional battery and external clock add-ons.

I don't know why, but even though the Aries Mini has a direct coax out which is a compatible input to my non-USB equipped Schiit Gungnir DAC, I found using the Mini's USB out to a MF V-Link 192 and SPDIF from the 192 into the Gungnir delivered better sound.  The benefit was NOT subtle...fuller, more-fleshed out, more engaging sound.  

BTW - I had traded notes about USB/SPDIF converters and, specifically, the MF 192 with Williewonka.  He provided info about Doukmall's low cost double-headed USB cable that separates power and signal.  

The Aries Mini and, arguably, the Gungnir are reasonably current.  From my perspective then, a USB/SPIDF converter continues to be relevant.     

The easy answer for me is, yes. In my system using a headless modified Mac Mini as a music server (Amarra, Audirvana+ and Esoteric HR Music Player). Using Esoteric K-03x and Audioquest Carbon USB cables (2). After extensive listening, which really in retrospect was not required, the SQ improved dramatically when I installed a Bel canto REFLink USB convertor. (Transparent Ref Digital link (OUT) to K-03x).
The USB implementation of the Esoteric K-03x is very good and current. Certainly worthy of the claim that, improvements can be had by achieving complete isolation from your computer. For me its a no brainer. 

Thank you all for the responses. It looks like a mixed field out there (as everything). Based on some of the comments here and other considerations, I went for a NuWave DSD DAC instead of buying an Audiophilleo for my DL3. I also purchased a WireWorld Starlight USB cable.

My consideration is that for similar price, I would gain advances in both USB technologies and DAC technologies. Every review I read comparing the DL3 and original NuWave said that the NuWave is a big improvement, so I am assuming the NuWave DSD is more?

@gocubs999 comment is interesting. I would be surprised the USB of such a device of the K-03x could be improved.. but apparently it could.

Regarding replacing my PC as a player, I've been wanting to build a custom player similar to the Bryston BDP-Pi.
I've already experimented with this a few years ago, with a RPi and HifiBerry which worked quite well. What I want to do is to build a linear PSU and put everything in a custom enclosure. I could connect that with SPDIF from the HifiBerry (like the Bryston) or via USB direct.

Plug your new USB cable into a good converter like the M2Tech or the Berkeley. Then run a good AES cable (I use MIT) from the converter to the new DAC. That will be better than running your USB cable directly into your new DAC.