Thanks JackD once more for pointing out the MasMusika site. I'm ashamed I didn't go and check there first, as I said, I bought a $3K digital piano from them a few years ago.
Michael, you are right about markup overpricing regarding cut foam! Alas, beside wanting to do all by myself, I have to actually work! LOL! So at some point chasing out all the foam sellers to see who carries the denser products and are willing to cut it will cost in work hours more than what I would be saving, specially for a $30 item.
So, I have bought the Presonus foams.
Initial impressions are positive: when I 'listen' to the residual sound that carries on onto the drawer, it is even cleaner than with my DIY ensamble. I'm surprised that the difference is not even grater though. My DIY product got me perhaps 80% of the absorption these pads provide. Anyway, it's an improvement nonetheless and I'm happy with that.
As an additional info / anecdote, the previous setup sounded one way when inside the room, and once you left the room the sound was less boomy and perhaps a little more pleasant. With these, the sound inside the room and the one carried outside the room is much more similar. So it appears that now it's mostly the speakers providing the feedback for the sound and less room 'interference'.
I am honored that Jason has made this into a sticky, mostly because that means that my own search for a coherent system may end up helping others in similar situations. But it's also a testament to the great help one can find in these forums, which would be really difficult otherwise.
Thanks again friends!