best way to chain these 2 units?

[Skywalker83]

Ok, i've got a Behringer Composer Pro XL and a ZOOM B2 coming in the next week or so and just wanted to ask which way would be the best way to chain them?

BASS > COMPOSER > ZOOM > out

BASS > ZOOM > COMPOSER >out

or use the side chain loop on the composer

BASS > COMPOSER (Send + Return to ZOOM) > out

[SpamBot]

Bass > out. Lol.
There is no "best way" to chain them, just experiment when you get them

[bongomania]

BASS > ZOOM > COMPOSER >out

This one. The Composer is not designed to take an instrument-level signal in, although it probably can. And the sidechain input on the Composer is meant for controlling the compressor's action from a different audio source, not the one passing through the compressor's audio path (i.e. not your bass).

The Zoom can probably boost your signal enough to get within the ideal operating range of the Composer.

If it doesn't work out this way then I would suggest going bass > Zoom > amp, and then putting the Composer in the effects loop of the amp. But it's probably fine either way. The main, most important thing is to carefully observe and adjust all of the input and output levels at each device to get a strong signal without distortion from each stage.