Gary.
it really depends on ones definition of warm.
ive got super clean diy mic pre's here that are as clean as a whistle
i built. useing very high end parts. 1db noise parts.
cant get any lower noise.
similarly some very high end mic pre's are ultra clean.
but the problem for some people is the sound is "clinical".

i had to laugh frankly. awhile back a whole bunch of people
on a high end recording forum who think de rigeur is one must spend
at least 1k on a mic pre were putting down the humble xenyx
mic pre's. so as a friend of mine didnt have many quids ,
i rented a xenyx just to see if the uber high end types were right.
(i'm a rebellious sort..lol.)
i put the xenyx thru its paces. recorded voc traks etc n compared
to voc traks ive done in hi end studios with megabux gear.
i came to the conclusion
the high end types had obviously never tried the xenyx.
cos i felt for such daft low money no one could complain.
getting back to your comment the thing i didnt like was it seemed
"clinical" once again.
as your aware theres a lot of BS when it comes to gear and marketing.
some people spend daft amounts of money searching for the ultimate.
i personally dont think of the mp as a super character mic pre.
to me it seems to provide just a little bit of character.

for over the top character awhile back i was trying to get for a fun
experiment an old stones vocal useing sorta a cokney style vocal.
in the original recording one can hear a bit of mic pre distortion or character
in the stones song. i couldnt get it straight ..clinical mic pre was too clean.
so i thought what the hey...bunged ..and your gonna laugh...
a guitar amp plug in on the track. fender bassman if i remember, twiddled a bit
with settings. n there it was , more a 60's old style vintage vocal with character.
much closer. weird huh ??

whats behind all this is (not me necessarily) some folks have the
"vintage sound" bug. so they spend large chaseing it.
but it can often be achieved with carefull use of a guitar amp plug in
if one chooses the right one for character.
ya know record 2 traks of vocs mebe.
put the guitar amp plug in on one..leave the other clinical n then balance to
get the amount of character versus clean one wants.

if i had the buks i would , instead of doing these kinda triks prolly
look at jlmaudio.com mic pre's.
ever looked at those gary ?? some folks love em.

retired puter engr....powertracks on amd......NICE !
"what is the black art of audio engineering ?"
my silly songs...motagator.com/bmanning
see my tips in the tips section.