"Warm" and "vintage" are terms that get tossed around a lot these days with recording gear. Neither of the brands you mentioned will yield those results. The Presonus, depending on the model, might have a more transparent and musical (oops, there's another one!), but the less expensive Focusrite gear ("Platinum") is very mediocre, over-hyped gear.
How much is the Presonus Eureka in your neck of the woods?

A shop I've done business with carries the Eureka for 37,500.00 baht, which, according to xe.com works out to 1,254.290 USD. Of course the baht is strong and the dollar is weak now, but that's a darn sight more than the $499 musician's friend lists it for.

Anyway, perhaps I used the wrong jargon earlier. What I should have said was that I'm looking for a way to add a bit of saturation and perhaps a slightly over-driven character that would lend itself to creating a nostalgic, gritty kind of atmosphere, reminiscent of late 70s jamaican recordings.

This is all fairly tongue-in-cheek, though, as I recognize software and plugins are sonically worlds apart from homemade power amps, modified consoles, and tape heads clogged with collie smoke residue.

Thanks for your reply,
ZVH

Check out the Groove Tubes Brick. Fits the price range and I think it could give you the sound you want.

I'm gonna throw in the ART Pro Channel here in this case. It will be the most vintage sounding of the bunch and will last well into the next decade without failure. I have spent some time with the Eureka and found it to be a bit limited. I like it on bass as a DI box, its okay for backing vocals and the sections all work good. Not a sterling piece but a bargain if you find a used one at a good price. The Focusrite is something I simply do not understand from a company that builds sweet and wonderful high-end gear.....It aint part of the family. The Pro Channel is tube based and has EQ, micpre and compression. In the right hands you cannot distinguish this things results from any other high-end device. In a novices hands, at least it wont make it harder to achieve a good sound.

Has anyone used the Joe Meek ThreeQ? It looks like a preamp, compressor & EQ, & the name alludes to a certain vintage vibe..

this may be my first post on this forum, but i figure i've got a couple good suggestions:

JoeMeek OneQ - the threeQ was already suggested above..the oneQ is a bit more expensive, but it's got a few more features that are handy if you're doing a lot of vocals, in particular a great compressor and the de-esser.

http://www.joemeek.com/oneq.html

Tech 21 Sansamp RBI - this is meant as a bass pre-amp, but I've used it with nice results on vocals a number of times as well. Since you state your main two things are bass and vocals, this might be an interesting all-around addition, as it's great on bass, and diverse enough to be used for vocals as well:

http://www.tech21nyc.com/rbi.html

Of course, the Tech 21 doesn't have phantom power so if you're driving a mike that needs it then hopefully your interface or mixer has phantom.

edit: just realized this is an ancient thread. ah well...still good info.