One thing is sure: sanderianum has a high percentage in the flower (I would say 50%). Then we have philippinense in the flower because of the red petals. The odd thing is that there is so much red in the pouch, otherwise I would have guessed that it is a straight Michael Koopowitz.
If roth is in this hybrid, it has a low %age, because roth hybrids have spotted petals (Habitus looks like there is roth in the cross tough).
I agree with the adductum. Paul Parks (sandie x adductum) looks pretty close already (especially the pouch shape of your plant shows adductum):
http://www.parksideorchids.com/images/Paphs/Paph%20Paul%20Parks.jpg
But there is much more spotting on the petals on PP than on your plant.
So you see it is very difficult to tell what is really in there. When you look at it for the first time you think it is easy to determine the parents, but after some time it becomes very hard actually.
I can tell you what I think it is:
Paul Parks x Michael Koopowitz
(adductum x sanderianum) x (philippinense x sanderianum)
So you have: 50% sanderianum / 25% adductum / 25% philippinense