building a DIY ad/da probably isn't a good idea. While it could work ok, there would likely be too many ways to bugger it up when building it. As stated by JDB, some parts need to be SMD for proper operation. Not only do they need to be SMD but simple things like having too much flux on certain traces can cause erratic behavior in some cases too.
There are other issues here too, like popular consensus. People like the OPAX134 parts but in reality those parts can't drive an A/D input well enough and your A/D might not sound as you expected it to. Surely though people would build them with those parts regardless and then there would be hundreds of pages of "why doesn't my A/D sound right".
I guess what I'm trying to state in simple terms is that this would not be the normal "populate the PCB and add power" project that we have around here. There are clocking/PLL circuits, specific loading, proper layouts, properly spec'd parts, and so on. That's not even taking into account the necessity for any processor control for everything. Someone who builds this would need a lot of test gear and the ability to troubleshoot mixed signal circuits or else they would have an expensive pile of parts that they can't fix in case of a non-functioning build.
