High resolution digital is dead. The best DAC's killed it.

And all the DSPro’s from Gen 1 were R2R

Sorry, but the Pro prime was only one of the Pro series to be Delta Sigma it used the DS chip SAA7350GP. The Pro Prime II was not DS it had 2 x PCM67P-K R2R chips

In fact, in 1994 i don’t think there were sigma-delta chips yet

Sorry again, but whatever you want to call it (Delta Sigma, Bitstream, 1 Bit, Mash ect ect ) In 1984, at the Eindhoven AES convention, that Robert Adams of dbx presented a paper on their 1-bit adaptive delta-modulation A/D- and D/A-conversion system.
I had "one" of the first DS based chips in 1990 the Technics SL-PS70

No, is not that simple.The cassanova card (at least the one i was holding) is also R2R.

Sorry again the manual and other sources states it uses for D/A 24bit Delta Sigma dacs and that they are 94khz compatible. Just as the Casablanca does also.
And the A/D section conversion is also Delta Sigma but just 20bit.

I had occasion to speak to the guys at Theta about the Casanova recently. According to them the DSPro is significantly better.

This is also correct, as the DS Pro’s except for the Pro Prime, are all R2R and not DS.

Cheers George

Does MP3 sounds better with better DAC than red book CD?

George:
02-15-2019 3:23pm

And all the DSPro’s from Gen 1 were R2R

Sorry, but the Pro prime was only one of the Pro series to be Delta Sigma it used the DS chip SAA7350GP. The Pro Prime II was not DS it had 2 x PCM67P-K R2R chips

read what i wrote, DSPro, not Prime, not Basic, DSPro. regardless, you seem to agree that the DSPros  were R2R, so what's your point?  Maybe I'm missing it...

And the card i was holding had a PCM17XX (i forget) R2R chip on it. Or a BB series that I thought to be R2R (e.g. 17XX, PCMXX) but that was some time back.

Now, as to when PDM/sigma-delta was in wide use (not in labs -- bear in mind that the Theta DSPro G2 is from 1993-4), i recall in 1987-1988 i was looking at the BB PCM54 predecessor to the PCM55 and 64 and it -- and the whole series to come -- was *very new*. BB was  in its R2R days.  Phillips was selling lots of what 1741s or something like that (ancient history!). But R2R was not special - it was simply how most things were done then.
I don't know what gen Cassanova i was holding or what variant - it was a card brought to me bare, with a project in mind. We scuttled that idea after speaking with Theta.
But regardless, my point was that the Theta DSPro was a significantly better performer to the Casanova i was holding, and according to the engineer i spoke with a Theta, the big differences was horsepower to perform the DSPs.  Maybe it was more - i didn't have the time or interest to play twenty questions with someone helping me.... So maybe it was PDM.

so what’s your point?

Take a pill sunshine. I said That the DS PRO PRIME was part of the "DS Pro" series and it was the only one of 9 in that series that was Delta Sigma, the rest all being R2R.

I don’t know what gen Cassanova i was holding

And that the Casanova was also Delta Sigma, it states it in the manual specs and online, here is the page https://ibb.co/zf4T5Xp
You must have been holding on to something else too tight.