I have the Onkyo 885 which is a clone of the Integra 9.8 and I am using an MPS-1 for an amp. I could not be more satisfied with the 885/MPS-1 combo.
The MPS-1/2 has the balanced inputs so you can take advantage of using them. Even there is no sound quality difference that I can tell, it does look cool

. One of the other nice things about the MPS is that it runs very cool. I have never heard the fans come on or even felt it get warm. The 885/9.8 gets very hot so give it several inches on the top and room on the sides as well. The IPS would be a good choice as well and should stay cool as it uses the same class of amp that is in the MPS.
I upgraded from a 72txv and was supprised at the difference is sound quality. With the 885/9.8 I heard much more detail in music and movies.
I don't know what sources you are using with the 9.8, but the REON does a great job for upscaling SD DVD's and TV.
Did you check to make sure it has the most recent firmware?