Why buy a DAC when you have a high end pre/pro?

More of the audiophile things. Sweeter midrange, depth, imaging, less congestion and so on. As always these sonic features may not be worth the price and hassle but only you know whether it's worth it to you or not.

I found that a $200 Cal labs tube DAC did all these things and worth it to me.

No SS processors or receivers currently match the quality of a good stereo DAC. I have one of the most musical ones, the Proceed AVP, and it is fine for movies, but my DAC's blow it away. Not even close. My system is world-class though, very resolving and low-noise. Completely modded out.

Audioengr: I took the time to read a review on your Proceed AVP (it was very complimentary) and one of the highly touted features was the internal DACs so I have to imagine that your external DAC must be really special.
I did start using my CDP as a transport and noticed an immediate difference (for the better) by using my Krell Pre/Pro as the DAC. I guess you start with the Pre/Pro or Receiver and then experiment from there and take note of what your ears are telling you. Budget also becomes an issue for most of us.

You are right. If you had a high-end processor like the Theta Casablanca, there is absolutely no reason to buy a separate DAC.

I've been wondering about the same issue for a while. I haven't currently delved in, so my comments are based on reading.

You can buy a used Proceed AVP or Theta CasaNova for less than 1000. Some commonly mentioned DACs are the Benchmark (around 1000), the Del Canto (2500) and the Musical FIdelity xDac (like 1500.)

So it seems a matter of how much you want to invest. A true high end DAC can exceed the price of a very nice pre-pro. So it makes sense that it would probably better the pre-pro when you consider the many functions of the latter. With that said, the pre-pro is pretty versatile and something like a used Proceed or Theta are big bang for the buck.

Just some thoughts.