I am afraid that you will need to be more specific. What do you mean by "round?"
"Maybe this world is another planet's hell?" - Aldous Huxley
Um..yeah....what was the question? Sorry I was a bit transfixed by the sight of Josh Homme and Trent Reznor in the same airspace.......

Ok, seriously. That's the tone of a hollowbody bass with most likely flatwounds. An Ampeg amp tone is also a guess here, though I'm not positive on that.
do understand your question about "round" sound.......however, I am new to this forum and have been out of "music" for 30 years and an getting back into it. I have a question about an Epiphone, Les Paul Special bass I just bought and I can't figure out how to "post new"........any help?
If you got pre-amps (active electronics) you can change your sound from there and make it more round to your liking. It`s also more easy for the amp to sound your guitar because of the electronics which gives you more control over the sound.
However there are certain strings which I have read to give you this more `round` tone and in the description they certainly used this word - `round`. So you might like to check how both the amp and strings work for you.
P.S. Note that the string with `round` tone is custom made and I`m talking only about the 5th or 4th string of the bass guitar, the others remain the same.
Hope this helped.
For a round sound, get some flat wound strings, any bass will do. Eq a Slight sad face if you have a graphic eq, otherwise turn the treble down a touch, mids up and leave the bass as it is. Its the opposite of the scooped metal sound.