This is my favorite DI. It's nearly the same DI as the JDI, but since it's active with phantom power—you can therefore use it with passive pickups—I find it more versatile. I've used it on stages large and small, and it never fails. It's whisper-quite, transparent, dynamic, and rugged. It makes any instrument sound good: I've plugged a number of instruments into this, including guitars, basses, keyboards, violins, and even a harp. Needless to say, the sound guys love these.
On more than one occasion a church has come to me asking how to improve their sound system without spending a ton of money, and in each instance, I've told them to start by dumping their cheap DIs and replace them with J48s. In every case, the improvement was immediately noticeable. If you're looking for a great general-purpose DI, and you don't need to the tone controls of, say, Radial's excellent PZ Deluxe, then the J48 is as good as it gets. I recommend it without reservation.
I use this direct box at church for amplifying a cello. Because it's an active DI, I'm able to get a strong, detailed signal out of the cello's pickup. Like all Radial boxes, it's built like a tank. Highly recommended.