Just thought that I would point out that the Denon 5803 has everything that you want - but its a receiver
so it goes against your whole philosophy.
I believe it has pre-outs so you can add a separate amp later. It also has at least 5.1 channel i think its got 7 or 8 channels of analog bypass for SACD/DVD-A.
its got the full set of Dolby processing(pro-logic/pro-logic 2, DD5.1, Dolby headphone) DTS etc.
high bandwidth component switching for HDTV signals
and a whole whack of stuff
Its Denon's flagship receiver - 'nuff said
review here:
http://www.hometheaterhifi.com/volum...er-7-2002.html
if you check dolby's site you'll see it listed along with a marantz. I would lean towards the Denon instead of the Marantz myself.
on a side note: you might try
www.avsforum.com - I think they have a forum (semi) dedicated to home theater PCs (HTPC) - although I think they typically only use the PC for decoding and de-interlacing the video and send the digital sound signal to a pre/pro (or receiver) for decoding. Some of them use an M-audio card.
I understand your want to "separate" components but taking it to the extreme may require you to either custom build some stuff yourself or convince someone to build it and sell it to.
As for one of your original questions regarding stand alone processors - it comes down to cost of implementation - why have an entire separate box to do Dolby pro-logic or Dolby digital 5.1 when one DSP can do both? With the average consumer snapping up home theater in a box and the large screen TV special of the week - most manufacturers want to cram the most features into one box so the average consumer doesnt have to worry about (gasp) wiring the DVD player to the TV and to the receiver.
As for separate standalone DD5.1 or Dolby pro-logic decoders there arent that many left on the market. Here are a couple that were available - you might be able to score one on the used market from someone who is "upgrading" to one of the new pre/pros with more features/channels.
Meridian 568:
When looking for standalone processors - one name immediately comes to mind - Meridian. Meridian typically has separate boxes for a lot of things. check out the review here for one of their older processors:
http://www.hometheaterhifi.com/volum...r-12-2001.html
check out the MSRP in 2001 ($6500 USD) ouch!
They have obviously updated their line of stand alone digital/surround processors - but I hope you have some cash cuz they cost alot
on a more affordable note:
Yamaha DDP1/DDP2 (1995/1998)
http://www.hometheaterhifi.com/volume_2_4/v2n4o.html
I think that Parasound at one point had stand alone ones as well another name is Millenium (I dont know if they are still making stuff) but they had a DTS decoder.
Some disadvantages I can think of are:
1. these are old - and as such are going to missing some of the newer features found in today's processors such as DTS-NEO etc etc.
2. DPLII is pretty new and from what I can tell a significant improvement on DPL1 - you most likely wont find DPLII on the stand alone decoders (the meridian maybe the exception)
3. you're going to need something to take in the decoded signals and pass it to your amp(s) - some use proprietary connections (like meridian)
FWIW - for my money - I'd go for an Anthem AVM20 pre/pro
