What is the best sounding Pre/Pro 7.1 channel with analog bypass.

How's McIntosh C45 or Krell S1200U compared to Classe Sigma or SSP800 or the AVM 40?

Interesting suggestion.  The AVM 40 is likely a very excellent contender for sound quality, however it's missing one critical element that would be a deal-breaker in my mind --- the ability to support the new bluray audio formats (DTS-MD and Dolby True HD).  It is also older than the Integra by about 5-8 years.  Kind of like buying an old Krell HTS or Showcase processor.

If sound quality is paramount, I agree it's better to find something used if you don't need the latest, greatest features.  Personally, I'd try to negotiate this Anthem AVM40, then stick a crowbar in my wallet and just buy it as long as it meets your needs.  Retailed for $3700 new. 

https://www.ebay.com/itm/192894634996?ul_ref=http%253A%252F%252Frover.ebay.com%252Frover%252F1%252F7...

Actually, that's a pretty good suggestion, if you want a new product.  The Outlaw 975 is very well designed and laid out as far as internal architecture goes.  It runs in the same league as the Emotiva UMC-200 did.  If you were looking at a new product, I would actually suggest the 976 model instead (for $929, which is well within your budget for "new").  It supports balanced XLR outputs and has much better power supply and power supply filtering - plus it supports HDMI 4K for future.
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That being said, I still think that Integra DHC-60.5 would be a better choice.  It has much larger power supply and much better components than the Outlaw (capacitors, transformers, etc.).  It is used, but you would get better sound quality in the end.  The Outlaw is built based on very similar principles to Emotiva -- to build the best design as possible using the cheapest components and sell direct to customer (no retail distribution) to give the best "bang for the buck" for the consumer.  They definitely succeed in that.  But keep in mind that Integra originally retailed for $2k (I just checked) and was highly mass marketed and distributed (which means it's still cheaper for a given performance that the boutique companies such as Bryston or Krell).  Integra DHC-60.5 comes in at 24lbs, where the Outlaw 975 is only 9lbs, the 976 is 12 lbs.

What about a new Outlaw Model 975 prepro since you're already running their amp?  Only $550. 

https://outlawaudio.com/products/975.html

I agree with big_greg.  Finding a good sounding processor WITH HDMI for $500 used is going to be very hard.  There's an Anthem D1 that has been upgraded with HDMI on audiogon for $670.  That's likely to be 15 years old.  The Integra DTC-9.8 that big_greg recommends can also be 12 or so years old.  

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for something newer, there's actually a Integra DHC-60.5 on ebay for $350 plus $99 shipping.  They say "barely used", but I wouldn't believe that too much.  But it's cheap and originally retailed for around $1600. 

My first reaction is to tell you to save up until you can get something better and not to expect great sound quality from a $500 pre-pro (or even much higher ones for that matter).

Having said that, Every time a new pre-pro comes out the manufacturer claims big increases in sound quality, when really it's mostly new features (room correction, video handling, atmos, etc.) and pre-pros tend to lose their value faster than most audio gear so you can find some bargains on some decent gear if you don't have to have the latest and greatest. 

In your price range for used, I'd try to pick up an Onkyo Integra DTC-9.8.  I'm not sure if it has all the features you want, and I'm not sure why you want to run the Oppo directly to your amp.  The pre-pro has balanced inputs and 7.1 analog inputs.  You can set it up so that you're using the DACs in the Oppo if that's what you're after.  There are a lot of reviews about this unit and a few of them for sale under your budget.

I looking to spend about $500 or less for a used pre/pro. So from $700 to $1000 new. Seeking clarity and imaging in the sound quality. Used mainly for HT, but want great sound for stereo. Using Chane bookshelf speakers with an Elac powered subwoofer in a 12'X12' room.  

What is your priority between stereo and HT?  What's your budget?  What sound characteristics are most important to you?  What speakers are you using?  Right now, IMO you're just organizing deck chairs on the Titanic.  Take a step back and let us know the answers to the important questions above and you'll get much better and more effective recommendations here. 

Hey Erik, he needs HDMI input/outputs.  Otherwise, I may have included P7.  But then again, he's asking for the "absolute best pass-through HT Processor".

Parasound P7.

No need for Y adapters. Its' a very good 2 channel preamp that has an extra 5.1. :)

It is much better constructed and sounding than the P5.

When talking about Y-adapters, you must be very careful.  You can use a Y Adapter to connect your Oppo or source to multiple amps.  However, you must never use a Y adapter to connect multiple sources to the same amp.  The signal will feedback into the second source and fry the output stages of that source.
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That being said, I would say either Krell S1200 variation or a Bryston SP3.  Both have slightly different sounds.  Both have fully discrete Class A audio stages for both input and output  Bryston has excellent bass, but it somewhat laid back in the mids and upper mids.  The Krell will not have as strong/deep bass, but it has excellent resolution and attack - much more exciting in my opinion.  The Krell can sometimes sound a bit bright/thin in some systems.