Marantz 8802a > looking for better two channel

Curious on people’s opinions and experience. I started out more into home theater but recently have been getting more into two channel. I’m running the marantz biamped into lexicon RX-7 into revel studio 2s with a pair of JL Audio fathom f212v2s.   There are basically no places to demo equipment where I live but I’m curious what level of two channel preamp it would take to be a significant improvement over what the marantz is doing. I’m running an oppo 105 with balanced connections as the main source.  While this may still be awhile out I’ve considered McIntosh mx150, lyngdorf Tdai-3400, or shoot for the moon one of the Current levinson preamps.  Also wondering if switching to any of those would then require a new amp to fully take advantage.  I plan to keep the home theater setup and do a pass through while keeping the subs in for two channel.  I like a pretty varied mix of music so not looking something thats great with classical but terrible for rock for example.  
I've been curious about the Lyngdorf myself.
PS Audio, Simaudio Moon, Parasound Halo are a few brand names off the top of my head; that won't disappoint.
I always liked McIntosh too, but I don't have the space.
The Lyndorph is not even distortion free for 16Bit. 
I doubt you will hear any benefit in “upgrading”. The target Audyssey curve isn’t that great, if you use it and don’t use Dynamic EQ, activate it, but change the Reference Offset from 0dB ro 5dB or 10dB.
If you get a quality stereo amp or monoblocks and a good preamp, there will be a very noticeable difference in sound quality. I went from a Marantz 8801 and Lexicon LX-7 to a Modwright LS-100 and Wyred 4 Sound st-1000 mkii (since replaced by rogue audio M180 monoblocks) and the improvement in detail, soundstage, etc was not small. 
The Marantz AV880x processor line are very nice pieces.  They have excellent power supplies and audio circuit design.  The sound is very solid and very full and very natural.  However, being Marantz, they are voiced very warm, which means the high frequencies are definitely rolled off compared to other preamp/processors.
The Lyngdorf is not going to be warm at all.  It is a very high resolution device.  However, when compared to Marantz, I think it might sound just a little bit thin and not quite as natural. 

I haven't directly heard the McIntosh, but I suspect it may be somewhat in the middle.  More natural sounding than Lyngdorf, and more high frequency resolution than the Marantz.
You may want to look at Krell Foundation.  That is also a very clean sounding modern processor.  My suggestions are all based on the assumption that you are looking to keep a HT processor in the mix and not go to a 2-channel only system.
However, being Marantz, they are voiced very warm,
Good thing EQ exists. However: 
Unless you consider changes within 1/2 a decibel to be easily audible, Marantz are dead neutral.
yeah, measurements really don't tell the entire story.  You can have measurements on a scope showing flat response to 20khz, but it won't really tell you if the amp is warm of soft or fast or bright.  I've dealt with warm amps before.  You can work around them with stuff like sliver fuses, etc., but it is a compromise at best.

What?!! I am showing unrefutable evidence that it is neutral, it’s not sane to claim otherwise.

‘Warm’ means boosted bass or rolled-off treble, it is 95% related to frequency response and 5% related to distortion.
I have personally had the Marantz AV8804 in my system and compared it to Krell S1200.  The Marantz is definitely warm with rolled off highs.
Thanks for the responses. I am looking to utilize the same speakers subs and amps but am curious on an a two channnel preamp that would be a huge step up in performance while having a home theater pass through and preferable bass management of some sort. I’ve also levinson 585 but not clear if that’s a big step up. Again really no dealers in my area so really going on reviews and forums for feedback.  
Subjective sighted evaluations =/= proof. I could listen to the same thing and say the Marantz is brighter than the Krell, a totally opposite opinion. However, we both would be wrong, as it’s neutral, proveably so. 
So I often find reading about audio like reading about wine in as much as terms which normally describe something else are often used to describe sound (bright, warm, etc). Is anyone aware of a CD which demonstrates these attributes in a way that any system could play and the listener would then understand the term better?
Subjective sighted evaluations =/= proof. I could listen to the same thing and say the Marantz is brighter than the Krell, a totally opposite opinion. However, we both would be wrong, as it’s neutral, proveably so.
Ah, so you’re one of those "if you can’t measure it, it doesn’t exist" type of people. That’s fine, I used to be just like that a long time ago, but after 20+ years in this hobby, I have learned that measurements don’t tell you what something is going to sound like. They may influence, but they are not the end-all. I will state again that the Marantz is warm. The high frequencies are there, but they are soft and rolled off, even though they are represented by measurement on a scope. They are definitely not crisp/clean like Krell or even Anthem.

Since you haven't even listened to the Krell/Marantz in comparison, you are just making an assumption and pre-judgement on what Marantz will actually sound like.