If you are open minded Oscar, consider leaving all that PCM just as it is - then convert to DSD128 on-the-fly. Your originals stay original and you have massive flexibility to let the conversion process evolve as your tastes, system and technologies evolve around those originals.
Case in point - I love the sound of DSD128 going to my current DAC. I used to use Jriver to do it, now I use something I think sounds better. I change over-sampling and modulator settings pretty regularly and the software seems to get upgraded (often with positive sonic effect) regularly. Some recordings seem to like different settings, system changes can shuffle the deck and as my computer hardware gets better, I'm changing settings. My current DAC goes up to DSD128 but a firmware change might change that, or I might get a new DAC, or a more powerful PC which opens up more setting options - it goes on and on. The main thing to note - those originals STAYED unmolested originals.
A year and half ago I first heard how good DSD128 sounded in my room and I experimented with converting a few of my favorite CDs to that format offline. Sounded fantastic and I was ready to buy a lot more hard-drive space and start spending all the time and effort needed to do it. I tried doing on the fly though and you know, I liked everything about it better. I now go back and listen to those first few converted files I saved and compare to the same source original converted on-the-fly with my crap in it's current state and they don't cut it - I'm SO glad I didn't bother with more.
On-the-fly is the ultimate in flexibility and with this technology changing and evolving at the rate it is, flexibility is a VERY good thing. It's also a 'tweekers' paradise and I know how much you like your tweeks Oscar!
Let your ears decide...but be ready for change - especially on the bleeding edge of digital.