Hi Donunus. It's very interesting reading your impressions throughout the month. Glad to see that you are still liking them.
Now, I know you were asking about a good setup for either the AD2000 or the HD595.
I do not have either, I have the HD650 and HF-1. I can't say if our musical tastes are the same, but personally I purchased the MHdt labs Paradisea and HeadAmp GS-1 for their compliments. The paradisea is a NOS tube buffered DAC, with not a trace of digital sound, but rather a nice smooth sound. The GS-1 is great in that it's quite neutral, and is giving me just what the music sounds like out of the DAC, while preserving the wonderful soundstage. I use this setup for both my HD650 and Grado HF-1, and they both sound terrific, just that the headphones are able to produce different sonic sigs.
I'm not saying this would be your ideal setup, but I would just like to mention these so that you can take a look at them and read up some more about them. Perhaps a bit more than you were hoping to spend, but if they do justice to your headphones in the end...... I have a funny feeling you could justify the price.
Keep us posted on how it goes!