I built the full tilt AudioNoteKits DAC 4.1 with the new triple C core output transformers. I also use an EL34 PP amp by AudioNoteKits. I like both units, and continue to use them daily in my system. Quality stuff, put together well, with great instructions. Sound is way above the price point of the kits. Plus you get the advantage to seeing what is in your unit, and how well it's put there.
That being said, it looks like PartsConnexion is moving away from the Audio Note parts, and AudioNoteKits (a Canadian outfit) is moving away from Audio Note iron (transformers, which have gotten very expensive). I am waiting to see if he moves away from Audio Note parts altogether. While there are "better" coupling capacitors now a days, there is a sweet music to the big AN copper capacitors that I am not eager to get away from. I always considered the AN stuff to be "brute force" simple, solid, circuits made with very, very good parts. There is a certain musicality to the gear which I fear will be lost with too many "better" parts substituted for the originals. I am hoping for him to be able to continue using the good stuff.