La Bella Black Nylon bass strings.

fretmeister

I got some on my fretless.

Just amazing. 

With the tone up - bright and articulate.

With the tone off - big, thick chewy old fashioned big band / upright tone.

Comparison vid of Black and White nylon versions

and a vid of the black ones on a Rob Allen MB-2

I tried a Rob Allen bass - stunning instrument. But not cheap.

Winny_Pooh

These are pretty Marmite. I thought they had weak output and not enough attack to be versatile. I now have a set of Daddario flats on my fretless that work pretty well.