Chino,
I have one of the LC ZapFilter Mk II output stages and have used it in both a Marantz CD-67SE and a Philips SACD 1000. It was much nicer than the original output stage of the Marantz. It lived in the Marantz for a while until I bought the Philips. I had the Philips modded by Stan Warren and while it was quite a bit nicer than stock I was somewhat disappointed with the sound.
I installed the ZapFilter in the Philips and was much happier with the overall sound. Very clean and clear without being harsh. The bass was full and articulate. Not as deep as I've heard but quite good and satisfying. Imaging was excellent with a good deliniation of the instruments and an excellent presentation of depth.
I'll put it this way, I would still be listening to it had my SACD 1000 not died. I felt no need to replace it and it sounded very good. I may take a stab a repairing the Philips one of these days but I had the opportunity to pick up the Parts Connexion modded Denon 2900 and I like the sound better than the modded Philips so my need for repairing the Philips is not pressing.

I am fairly certian the ZapFilter would better the existing output stage of your 963. One thing to keep in mind is you have to find room to mount the power supply in addtion to the Zapfilter. This amounts to a small toroid transformer about 2 1/2 inches in diameter and a PC board about 1 x 3 inches in size. If the 963 is similar to the SACD 1000 this means you will have to remove 4 surface mount resistors and solder the input wires to the pc traces where the resistors were. This can be challenging as they are not very big.
Hope this helps,
Mike G.