not knowing what your network set up is, hard to say; for two channel audio + the 802s, (I suppose you are using the krell/mcintosh combo for Home theater or multi-room? -- for audio only its a little "unique" as a set-up)
If I had your set-up (provided that the McIntosh/Krell is not used for just audio; multichannel is required, and I liked the DAC in the Mcintosh as much as you do!), and I had 10k$ in cables/interconnects (and not 10K in yen) I'd sell them and put the money into the software r-cohen recommended combined with some good measuring gear, with a multi-channel interface from manufacturers like Steinberg, Lynx or others. The problem is the learning curve is steep if you want to do this yourself. I haven't had the time or money to get into that myself -- looks like it would be under 2000$US so all things are relative of course.
With the Krell you might even be able to go "active" with convolution filters and such, but the passive crossovers in the high end BWs are really so good not sure it would be worth it.
@Mods - might want to move this out of the Windows 20 forum?
So like people are saying above, changing the computer won't give you any significant benefits in my humble opinion - other than output choices (which could be important), looks, and options that you probably don't need. But I don't know your entire system, so take everything I just blabbered about with a grain of salt