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.  
esthlos13
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.  
@auxinput 
 
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?