I always wanted my electric bass to sound like a Double Bass, but way easier to play and carry and amplify. So I have played fretless since 1974. Then I heard Jaco and it was all over.
Starting with the instrument itself, the more wooden sounding and full range the pickups are, the better. I always like real Ebony neck to resonate, but Michael Manring gets a lot of mileage out of a Carbon Fiber neck.
Most guys here like the round wounds, I like the Tomasik Invenld Jazz Bass strings for that. Lately I have been liking the La Bella Deep Talking Bass nylon tape wounds. Cool on a black ebony neck.
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For amps, the preamp is important. I need a tube preamp, either built-in or as an external pre like the ART Tune MP. That brings out the woody tone.
I noticed consensus about using 12" speakers. Thats all I will use for any Bass, though a quality 4x10 makes sense for the mids. I love my Avatar SB112 cabs
http://www.avatarspeakers.com/sB112.htm
I have two, one for smaller gigs, a stack for larger gigs.
From the other side of the aisle, band leaders often tell me they HATE the nasal midrange honk of most fretless Basses, especially when played sharp. Dude, don't be a Honky! Fret so that the right side of your finger lines up with the note, not the middle of your finger. Otherwise, your fingerboard finger on the "fret postition" is sharp by half the width of your finger.