On the bottom of your device on the big white sticker you can see which version you have. If the item number starts with DBU and ends to 1 (DBU-8501-1), then you have a DBU1GEN. If it ends to 2 (DBU-8501-2), then you have DBU2GEN. If it ends to 3 or 4 then you have DBU3GEN.
- DBU1GEN: This was the first generation. It has some config files (less than 10), and can be updated with a firmware, that can't be downgraded (it adds station following, which by the newer models are already included).
- DBU2GEN: compared to the first generation it had a new hardware and software. Although it had no firmware updates, only the 16 configuration files. (The config files of the DBU3GEN were not made to be compatible with the DBU2GEN, but some end users could install some and could reach success.)
- DBU3GEN: This is the actual version. It's hardware is the same as the DBU2GEN, except that starting from DBU3GEN Dension makes also the parts of the device, they come not from a supplier anymore. It has a newer base software, all the current DAB+U configurations can be used here and also firmware updates are available.
If you play the About.mp3 on your DAB+U, then as ID3 information you can see the current firmware version, which also tells you which DAB+U have. If the firmware is starting with DBU2x.xx then you have a DBU2GEN, or if it starts with DBU3x.xx then you have a DBU3GEN.
Nissan:
All of the above mentioned DAB generations have a Nissan version too. If you check the bottom of the DAB+U device and if you can read on it "DAB-USB Adapter FOR NISSAN IAM", then it is a Nissan version.
- DBU1NI1: The hardware of it was a DBU1GEN, but it had a different software base, so the firmware update and the configs of the DBU1GEN can't be installed to it. In the factory they were preconfigured to Nissan.
- DBU2NIS: This is a DBU2GEN, the only difference is that instead of the default K3 config a Nissan config is installed to it. You can install on it the configs of the DBU2GEN to try it in other car brands.
- DBU3NIS: This is a DBU3GEN, the only difference is that instead of the default K3 config a Nissan config is installed to it. You can install on it the firmware update and configs of the DBU3GEN to try it in other car brands.