"Line" as in "DI" signals from the output of syths, etc.? There is no shortage of them... Chandler, Great River, Phoenix Audio, Aurora Audio, API, they all do it.
What I would suggest is that you find a tool that fits your sense of aesthetic for whatever project you're working on... which will mean you'll have to take some time and try out a ton of stuff but that is true for any and every piece of equipment you add to your studio [or at least should be]
Best of luck with the search!!
