Passive/line stage HT preamp?

"Actually, I guess a better way to ask the question is can I go directly from the analog outs of the Oppo to my amps? Do I lose anything that way?"

The Oppo has a volume control that works in the digital domain? Such controls theoretically lose resolution as the volume is reduced. You may prefer to insert a preamp that has an analog-based volume control like the Parasound P7 that Kal mentioned.

Other affordable candidates are the McCormack map1 and the bel canto 6 channel preamp that occasionally shows up used.

It appears that you are looking for volume reduction only from a single source to your amps. There are a couple of potential downsides to using digital domain volume reduction from the oppo. In addition to loss of resolution as mentioned above, you need to consider if your source can drive the amp. This means you will need to consider the input impedance of your amps -- the higher the better, usually, if you are above 40 kOhms you will be ok, and the output impedance of the oppo-- at least a 10:1 ratio is desirable, so lower than 4 kOhms if the amp is 40.
TVC passives are good choices, and tend to be pretty good with driving amps properly. Check out Sam Telligs review of the Promitheus Ref in this months stereophile. I used that TVC for years and really liked it, then replaced it with the even better Promitheus Signature. Both of these are great values and dead quiet of course.

>> he Oppo has a volume control that works in the digital domain? Such controls theoretically lose resolution as the volume is reduced. <<

Except the Oppos use 32 bit internal processing for the volume control. Even if you turn the volume down significantly, you'll still have at least 24 bits of resolution. The Oppo's digital volume control is a very good one, I would not sweat this "issue"...

-RW-

I still think this comparison "shoot-out" NEEDS to be done at some point! I really do..
How many times over the years have we heard enthusiasts and audiophile’s alike discuss the topic of "bypassing an outboard AV pre-pro, and going multi analog ch source out directly into a power amp's inputs" -processing, strictly in the source component?
At the very least, there are many out there - purists? - who feel that the best possible sonic performance comes from doing a passive system, whether is be a stereo setup, or multi channel setup. And, regardless of the source - whether it be analog music or digital movie sources - this is the end-all of sonic achievement, period!
I for one think some A/B testing "shootout" NEEDS to be done here, in an effort to see/hear what's what?!
My experience with passive 2 channel music systems over the years, was that you trade dynamics and presence for tonal clarity and lack of coloration when you use a passive setup (no preamp in the chain). I've also personally found similar effect, using direct (passive) analog out from my past DVD players over the years -bypassing the outboard dedicated pre/pro - straight to multiple amplifier inputs, particularly for digital 5.1 channel processing...basically rather flat, dynamically, if super clear sounding.
So, what's the deal here!?! I still hear so many people stating that they don't think using a surround processor in they home theater system, is the best path to the best sound quality. Does anyone else out there find that the benefit of one less piece in the sonic chain to color the sound is outweighed greatly by the fact that the dynamics are severely lacking with a passive setup approach? - basically letting these OPPO'S handle everything redbook cd's to BluRay 7.1 HD tracks, internally?
Who'd care to chime in here with their experience? I mean are AV industry expert reviewers using pre's and AV receivers in their reference systems for the mere convenience of having source "switching", EQ's and volume control in the system, at the sake of absolute sonic purity? ..or are we missing something here?