Is 24/192 all hype?

Sorry for the flamethrower-bait thread title, but I wanted to get people's attention. I have a couple of threads going in the HT forum about trying to integrate a HT capability into a two channel system, and there's a bit that needs to go here.

I have a Marantz DV8400 that I'm using as my source (maybe to be replaced with either a 9500 or Onkyo SP1000 soon). Now it has the DACs and DD / DTS capabilities - even decent BM - to kind of question the need for anything but a multichannel analog preamp. Here's the BUT: but if I already have a HT prepro that has only 20 bit DACs and ADCs and no MC analog bypass, do I really lose audio quality (assuming the quality of the prepro converters is better than the 8400) by running the analog of the 8400 into the prepro? If I run a DVD-A or SACD in this mode do I really "lose" something?