New to Preamp - Preamp suggestion around 10k

@mulveling: David Manley was also active in the Pro Audio sector, as was Tim de Paravicini (Pink Floyd’s studio, Kav Alexander’s Water Lily Records fantastic tape recorder, on which was recorded A Meeting By The River album). I have an old friend (they’re all old ;-) who has a Manley mic pre-amp in his recording studio, and loves it. I’ve spent some time conversing with EveAnna at a coupla CESes and Stereophile shows, and found her to be a very cool, interesting person.

https://tmraudio.com/components/preamplifiers/luxman-c-900u-stereo-preamplifier-c900u-remote/

TMR has the Luxman C 900u.  I purchased same unit from them months ago.

I own 2 LA-4 pre-amps from Benchmark Audio and Love them. Considerably cheaper than 10K. With remote (metal) about 3K     free shipping, 30 day trial period, 5 year warranty, USA upstate NY, been around for ages   Rory is excellent to deal with.  did I mention balanced     What do you have to lose?    A human always answers the phone and promptly too.  Robert TN

@cming0038. Thanks for clarifying that you have top of the range Stax equipment.

To be frank, I don't think what you are trying to do makes sense. The only thing the bypass function on the 8000 does is to remove the volume control from the circuit. So your signal will still be going through all of the 8000s amplification circuitry and all you will be doing is to precondition the signal by putting it through a preamp before you input it to the 8000.

I don't think that will radically alter the sonic character of the 8000 though that can only be known by trying it, I suppose.

Though I rarely recommend buying two of anything, you might be better investing in an alternative setup with a top quality pair of dynamic headphones. You may have done that already, but you'd description of what you want to change in the Stax's is, to me, fairly reflective of the basic differences in character between electrostatic and dynamic designs.

I haven't heard it myself, but am interested in knowing how many would consider a BAT VK-80 to have a slight bit of warmth the OP is inquiring about.