Forget about balanced outputs. If they were meaningful, Don would design his preamp for them, but he feels RCA outputs are perfectly fine.If you hear balanced line done right, there simply isn't any going back to single-ended. More detail, blacker backgrounds... One advantage of balanced operation is the interconnect cables between the preamp and amp won't be a big deal any more; if you've ever auditioned cables to get the best sounding one in your system you know what I'm talking about. You can also run longer distances as well, but that blacker background benefit is still there even if the connection is only 6 inches.
The thing is, there is a standard for balanced line, which many high end audio manufacturers don't seem to know about. Its called AES48. If you want the benefits of balanced line operation, make sure that you ask the manufacturer if their gear supports AES48.