There are numerous options depending on your goals and your budget. Here are a few categories with examples. Keep in mind each category offers dozens of options so do your homework and decide what's right for you based on preference and budget.
Standard Passive DI:
This type of direct box requires no batteries or phantom power and is the most basic. It will do a fine job delivering your bass tone with little coloration. Some pro-grade passive DIs include:
- Whirlwind Director
- Radial PRO DI
- Radial JDI
- dbx DB12
Active DI:
This DI looks just like a passive DI but has active circuitry which requires a battery or phantom power. Active DI boxes are useful for driving very long XLR cable runs and often have a more open top end sound when compared to passive. Some pro-grade active DIs include:
- Countryman Type 85
- Radial J48
- Radial JDV
- BSS AR133
- Avalon U5
Tube DI:
A Tube DI looks quite different than your average DI box but it essentially performs the same function while adding a tube to the signal path. There are many different ways to incorporate a tube so each tube DI has its own character but you should expect additional warmth and even order harmonics from any good tube DI. Tube DIs will also be the most expensive. Some tube DIs include:
- A-Designs REDDI
- Demeter VTDB
- Radial Firefly
- Sonic Farm Je-DI
Bass Preamp DI:
This takes active to the next level by incorporating a bass preamp and DI into one compact unit. Additional features can include EQ, Amp simulation, overdrive, compression, etc. Some examples include:
- Aguilar Tone Hammer
- Sadowsky Preamp/DI
- Eden WTDI
- Tech 21 Sansamp Bass Driver DI
- SansAmp VT Bass
Again, there are lots of options and opinions and these lists are certainly not comprehensive by any means. That said if all these possibilities make your head spin, you can't go wrong with a good passive DI.