I already posted this on the Andy Sneap forum, but here it is:

Someone asked if there is any difference in DI-boxes. I took the preamp out of equation and left it at the same position, di-boxes have all features disengaged and no pad's. When I added a IMG Stage Line DIB-100 passive DI-box to the test, I think you can clearly hear the difference, it just doesn't have hot enough output compared to the active boxes so I added a version where I opened up the preamp for the passive DI.

So I came to a conclusion that when choosing a DI-box for tracking guitars, choose an active DI. The differences are pretty minimal within certain models. I compared:

Radial J48 (active)
Behringer DI-20 (active)
Sansamp Bassdriver DI (active)
BSS AR133 (active)
Behringer DI-100 (active)
Millenium ADI-6 (active)
IMG Stage Line DIB-100 (passive, two takes)
Samson S Direct plus (active)
Hosa DIB-443 Sidekick (passive, two takes)

First with lo-gain sound, then with hi-gain sound: http://dl.getdropbox.com/u/1338211/di_comparison_incontext.wav
DI only: http://dl.getdropbox.com/u/1338211/di_comparison_dionly.wav

As you can hear, there is major difference atleast in the output volume of the DI-boxes

Nice shootout, cheers! The DI-20 and DIB-100 were the ones that sounded the most different to me, and not in a good way :/ Not surprised about the DI-20, though, I've heard nothing but bad stuff about that one.

I added Samson S Direct plus and Hosa DIB-443 Sidekick to the test (files are still updating), I tried and used the J48 as benchmark and the volume or tone hasn't drastically changed eventho there was 2 days in between. The Samson was pretty bad in the output volume but considering that the Hosa is passive, it was actually pretty nice in both signal to noise ratio and output volume, I only had to open half as much preamp as with the IMG passive