I have a Herron Audio VTSP-360. Keith doesn't put XLR connections on any of his gear. It sounds fantastic. Before that I had a Modwright LS 100. While it had XLR connectors, it was not "balanced". It did however also sound great.
How does your system sound? Another preamp might sound better than the one you have, but whether it is balanced or not is probably not going to be the reason it sounds better.