If you do a lot of gigs where you're using your bass amp on stage but also going through the house/band PA, where you've never really been happy with the bass sound from the PA or in your monitor, then the Radial J48 is the box for you!
After years of cheap DI boxes or using the crappy DI out from an amp, the difference in using this box is night and day. I play mainly passive basses, so this active DI box gives the signal a fat boost that sounds great in a live mix, giving you tons of confidence that your tone is shining through.
The mark I gave on features isn't negative, it's just that this box doesn't need any and does its one job very well. It runs off 48V phantom power from the desk, so no batteries required. There is also a 15dB cut if the signal you're giving the desk is too hot. Other than that it seems rugged, hard wearing, you can run all your effects through it prior to going to the desk and it handles it all perfectly. If for any reason I had to do a gig without my amp, or the house amp at a venue was broken or really bad, I'd be very confident that I'd get a great sound just by plugging into the J48 and going straight into the PA.
In addition, it's a great tool for recording - the clarity and tone that comes through is so good that it will easily hold its own against mic-ing a bass cab, and of course works great with the two in combination.