How to evaluate CD DAC vs. outboard DAC quality

"So the question is: How can you know whether a recently released DAC (say around $1000-$1500) will be a useful add-on? I'm not looking for the flippant and unhelpful try-it-for-yourself-and-see response."

I understand that you are not looking for that answer. Given the question, though, I can't possibly think of any other answer that's accurate. There are so many factors involved, there's just no other way to do it.

I can think of one thing you may want to try. That is to stop reading equipment reviews. It may sound like an odd suggestion, but I'm being serious. You just don't need them. If you really want to learn about audio and become good at selecting components, getting rid of the reviews is probably the best way to do it.

My personal experinces:
I own a Sony SCD777ES. Using that as a transport into my Adcom DA700 (about 12 years old, bought used 7 years ago for $250) I tweaked it with antistatic foam, and NOW (after this comparison test) run it off an AC source at 110hZ instead of 60hz
My Adcom DAC is about the same sound quality as the SCD777ES direct.
The SCD777ES NOW (after a few tweaks to the system, sounds just slightly better, but just barely)
I own Magnepan 3.6 speakers, Bryston 4B-SST2 amp, Bryston BP-26 preamp, VAC Standard preamp used as a glorified tube buffer for digital stuff Furman REF20I conditioner. A PS Audio P600 conditioner set to output 110Hz instead of 60Hz A/C for the digital stuff.
So I have decent equipment.

Anyway i bought a Bryston DAC, the hot new (at that time)DAC raved about Stereophile class A, and TAS recommended DAC. It was $2,200. So I tried to compare the new DAC to my old one. I could not note anything better about the Bryston DAC.
I tried!!
Finally I wondered if some shortcoming in my other (Then) new stuff was holding he DACs back?
I got a Bryston BP1.5 phono box I had to order, and was relieved to hear a spectacular sound, So at that point I knew it was not the pre, amp and speakers holding the DACs back.
I retuned the new DAc for a refund.

So that is MY experience. with damn fine equipment, I could not hear any difference between an over ten year old DAC and the hottest raved about new DAC.
All these 'flavor of the day new little statup company DACs claiming to be the hottest thing since whatever.. ?
Yeah right.
So I doubt you (the op) will note much difference adding a DAC. It may have a slightly different flavor, but it will not actually sound 'better' in any meaningful way.
You would be better off buying some other doodad. like a power conditioner. or some better wires.
This is my experience.

If you want greater musical realism, get better speakers.

I was using a Sony 5400 as my digital source. Then purchased an Audio Note Kit Dac 2.1b for $1750 using the Sony as a transport. Major inprovement over the Sony especially in information retrieval and frequency extension. I have now replaced the Sony with an Audio Note CDT Two/II transport. Another major improvement proving to me that the transport is just as important as the dac
Alan

I agree with Elizabeth. Newer isn't akways better and there are other factors involved in how a dac sounds besides the chip used. It's like a quality 100 watt amp sounding better than a crappy one that's rated at 1,000 watts. I can't hear a difference between my parasound z-dac (which got and is getting rave reviews? And my musical fidelity a3.2 cd player (that got ok reviews). Buy a dac that you can return once you've heard it then you can decide for yourself!