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if this is a new to you violin, the bridge could be cut different or wrong, the finger board might be grooved, the nut might not be notched correctly. Its also poosible that the string is not seated in the nut or bridge properly.
On an outside guess, it could be your fingerboard not cut/formed properly. Any of these could cause the string to sit higher.
"I find your lack of Fiddle, disturbing" - Darth Vader
Different brands of strings produce different volumes and react to bowing differently. It is possible that the previous owner broke a string and put on an older used string or some brand that has a bit less volume and/or response.
I'd agree with Iaen that a fresh set of strings would be the first thing to try. Sets are usually reasonably well balanced for volume.
If that doesn't do it, well then if you put up a few closeup pics of your violin maybe some of the members will spot things you can try adjusting. Ty gave you a partial list of things that might be wrong, so you get some idea what it might be if a fresh set of strings doesn't fix it.
"This young wine may have a lot of tannins now, but in 5 or 10 years it is going to be spectacular, despite the fact that right now it tastes like crude oil. You know this is how it is supposed to taste at this stage of development." ~ Itzhak Perlman
@ remline; As Daniel said, it's possible that the previous owner put on an older worn out string. It's also possible that your D string could be aluminum rather than silver. Another possibility is that if the owner did happen to change the D string that he replaced it with a heavy tension string which can produce a duller sound and need's brightening up using a medium tension string.
Replaceing the whole set first is where to start. Another thought is that your sound post may need to be reset, the location of the sound post, even by as little as 0.5mm can affect the sound greatly. Moving the sound post from side to side will change volume, from bridge end to fingerboard end will change the tone. Moving it in one direction and the violin will give off a tinny sound, much like a horn. There are so many variable's in sound production that it's unreal.
Good luck with it and welcome to the forum.