Home Theater Bypass , why am I hearing this now.

A preamp or integrated with HTBP will allow you to get the most from your music listening (assuming a quality preamp or integrated) than you'll get from a home theater receiver or processor.  

When listening in two channel, the home theater processor is not used at all.  When watching movies, engage the HTBP and your front two channels are powered by whatever you're using for two channel amplification, and your home theater processor manages the signal processing for all channels.

Opinions about whether a two channel or multi-channel home theater system are "better" are just that - opinions, not facts.

big_greg,
"When listening in two channel, the home theater processor is not used at all. When watching movies, engage the HTBP and your front two channels are powered by whatever you're using for two channel amplification, and your home theater processor manages the signal processing for all channels.

Opinions about whether a two channel or multi-channel home theater system are "better" are just that - opinions, not facts."

Totally agree. 

I think "Home Theater Bypass", almost by definition, refers to a 2-channel preamp or integrated with a pass through feature in which the signals from a HT system pass through the 2-channel system directly to the amplifiers/amplifier section without modification.

If you do not have a 2-channel unit in you system, HT Bypass is irrelevant.

If your priority is 2-channel sound quality (which only YOU can determine), my opinion would be to build a 2-channel system with a preamp/integrated that has a HT Bypass <http://www.audiophile.no/en/articles-tests-reviews/item/426-amplifiers-with-processor-input>.

Your 2-channel sources would be run through this unit.

Your HT sources would be run through your HT unit. Left and Right front outputs from your HT unit would be fed into the Left and Right HT Inputs of your 2-channel unit.

With respect to your comment, "AVR HT receivers will never get you a tru HIFI experience because of the processing that takes place and a dedicated 2 ch is the only way to go"--I don't think that's a fair statement.

First, only you can determine what a "tru HIFI experience" is.

Second, can you say with 100% certainty that all HT units "process" all input signals the same way?

For example, and this is just a hypothetical: Marantz has been well respected in the 2-channel world since the stone age. Marantz makes HT units with traditional 2-channel inputs (analog, phono, maybe even tape). Why would Marantz "process" these signals instead of just sending them to the outputs or amplifier section?
Why would Marantz take a phono signal input (most likely in stereo) and try to convert it 7.1 HT?

It seems to me that they would want to do the exact opposite, and let you know about it! They want to appeal to the widest possible audience so they are going to emphasize the HT and 2-channel capabilities.

Now, as with everything else in this hobby, it's up to you to determine if the sound is "tru HIFI".

Did I hear my name mentioned? lol.  Just kidding.

I will disagree with maxwave here in the idea that most HT processors will add "coloration" to the system.  There are some that may add some coloration, but for the most part HT Processors are engineered to be as fast responding and transparent as possible (this is really needed for movies). 

The Marantz processors are actually quite excellent for the money.  Large power supplies and good full bass / midbass.  Good overall impact on sound.  However, like all Marantz, they are voiced just a tiny bit warm and will soften/roll-off the high frequencies.  If you are looking for better high frequency resolution, you can do one of two things:

1. Change to a different HT Processor (possibly spending upwards of $8-10k even on a used one).  This will get you better resolution for your stereo hi-res than what the Marantz offers.

2. Put in a preamp and use HTBP mode when watching movies.  This is just a preamp connected between your HT Processor and your amps for left/right speakers.  When the preamp activates the "home theater bypass mode", it essentially just makes a direct connection between that input and the output of the preamp.  This is almost the same as a direct wire connection as if the preamp wasn't there at all (the audio signal does not go through the preamp audio stages at all).  When you want to listen to a hi-res DAC or streaming source, just switch the preamp to that source and it "takes over" the sound duties for left/right channel.

Make sense?

If you go the preamp with HTBP route, also be aware that many preamps are much more colored than HT Processors.  And just because you get a preamp doesn't mean that it's actually going to sound better than some processors.  For example, the Parasound P6 (or even superior P7) will not match the sound of some HT Processors such as Bryston SP3, Krell S1200 - or even the Krell Foundation and McIntosh processors.  The Bryston SP3 and Krell S1200 actually have discrete analog stages which are at the high-end 2-channel preamp level.  The only way to beat those would be to get a dedicated Bryston/Krell preamp.  The Krell Foundation 4K processor would beat the Parasound P6 preamp.  But then again, there are still higher end preamps out there that would definitely beat Krell Foundation.

So, in the end, if you are happy with the TV/movie sound of your Marantz HT Processor, then you may want to consider the preamp / HTBP route to really give you a boost on 2-channel audio sources (i.e. Denafrips DAC).

If you want a better TV/movie experience as well as better 2-channel audio, you may want to consider a higher resolution HT Processor instead.  If you are willing to consider used, I would go for the Krell Foundation 4K at a bare minimum.  But if you are willing to spend upwards of $8-10k, I would look at a used McIntosh MX160 maybe.

@auxinput
I knew your were the right guy :-)

By coloration , I included the averadge quality electrical isolation and vibration control of a HT processor compared to highend integrated amplifier or preamp with HT bypass.
There may be a difference in these matters between a 10k HT processor and a 10k integrated amplifier or preamp.
When using analog inputs of a HT processor , the DAC of the HT processor will not be used.
The sound quality will depend on the other components of the HT processor

But I have been wrong before ……