Have DAC’s improved for Redbook CD playback?

OP, interesting question. 

IME, yes and no. It’s a very broad question, so the main answer is, “it depends”. ... on all the factors pointed out above - input and output stages, psi, DAC chip. 

I always used to assume products would evolve and evolve and get better, but I was wrong. Manufacturers (not high end like ARC, ETC) May advertise a NEW DAC chip, a new this or that. But often times, for every penny they put into the DAC to improve it, they will cut costs elsewhere in the DAC to increase profit margins. 
Two steps forward, one step back. 

But jitter control in commercial products has been improving, and probably one of the biggest recent tech improvements to improve SQ. 

IME: 
i have a Bel Canto DAC 3.7 with external PSU. I can feed the DAC from a SimAudio CDP via SPDIF or feed the DAC via computer via BEL CANTO Ethernet Renderer. 

1. The sound from the CDP is very good, since the Sim is also an excellent transport. 
2. But the signal going from the Mac via the Renderer to the DAC is a different ballgame altogether. 

3. In other words, although the DAC 3.7 is excellent in and of itself, BUT it is the Renderer that takes the DAC to a whole new level in every way, but especially soundstage. 
4. So then Bel Canto took all their tech (Renderer, jitter control, DAC and Class D amps, etc) and put it all in one box for $15,000.

Bel Canto THEN  DCed the DAC 3.7 and the Renderer, because that combo is so good that is was slowing down the sales and hype of the BC “Black EX” - $15000 all in one unit.

So, does the BC Black EX offer a “better” DAC than the 3.7?
Most likely, but only marginally and for a much greater cost. 

sell off my digital front end for now.

Please PM me with a price for the Theta DS Pro Basic IIIA

Cheers George

I think the biggest improvement modern DACs have made over older DACs is reduced jitter. Most DAC designs nowadays implement some sort of jitter correction.

I just resurrected an old DAC that I had and put it in a different system and am very pleased.  I had a PS Audio Digital Link 3 sitting on a basement shelf.  It’s about 10 years old and was formerly in my two channel system.  It’s major weakness was that it didn’t have an asynchronous USB, and as I started to get into computer audio that became a liability, as the usb sounded awful.  I had bought some sort of reclocker device from Musical Fidelity that was a very unreliable device and ultimately I added an Oppo 105 to my system and began to use the Oppo as my DAC and kicked the DLink to the curb.  I meant to sell it off but forgot about it
  My 14 year old Plasma display broke in my Surround Sound System .  The Oppo had been moved to this system but now it was
incompatible with the new 4K display.  I swapped an Oppo 203, which was doing transport duty in the 2 channel system, for the 105 in the Surround system, since the 203 is compatible with the newer display.  However, I had been using the 105 as a DAC for a Bluesound Node2 in that System, and the 203 was clearly a step down from the 105 as a DAC.  So I dusted off the PS Audio DAC and it was a Wow! moment.  The Node2 just snapped into focus.
I then used the coax out from the 203 into the PS Audio DAC and Redbook CD from the Oppo 203 sounds great, much better than from just using the 203 DAC.
  So are newer DACs better?  I don’t know, man.  There is a lot of life in some of these old geezer components.  Now, if that was only true for their owners ad well...