Behringer BDI21 level when recording with Delta 1010 DAW

Hi all, first post.

I'm trying to use my Behringer BDI21 DI modeller / preamp to record on my DAW with a M-Audio Delta 1010 soundcard.

I originally had it connected from the BD121 balanced output to the 1010 via a XLR - TRS cable. But the signal was very quiet, even when I flicked the -10 / +4 button on the Delta

I tried using the unbalanced output via a standard patch lead, and it was louder, but still not anywhere as near my other tracks.

Have I missed something here? Why is the signal so quiet compared to, say, the guitar signal from my Behringer V-Amp?

Interested to hear any comments.