I expect it is really not set up for line-level (FX-loop) signals, which is probably why the guy developed issues...
Running it through the amp doesn't help you anyway, since there is no way to return the signal to the FX-Return.
Using the DI-out into the recording interface to obtain a balanced signal usually helps reduce hum, IME.
I have a preamp (B7K) with a 'parallel out' jack - something like that might allow you to drive both the amp and a recording interface simultaneously...
I didn't see any mention of input impedance for that device, which could affect the signal quality, especially the highs, especially if you have a passive bass. This is another reason why plugging into the computer sound card mic input is usually suboptimal - but it might be worth a try...
I'm at a loss to explain why your DI->XLR cable->interface method produced bad sound, although the Behringer's connector is labelled "mic preamp" so maybe it's not actually suitable for a DI-level signal, or again, the impedances are not well matched. In which case - I think I'd try plugging the instrument into either the 'mic Line In' or 'Line 2' jack.
"It's not supposed to be" this difficult - but I have no experience with your interface, so I really have no better suggestions than "try stuff" and read the manual...
Running it through the amp doesn't help you anyway, since there is no way to return the signal to the FX-Return.
Using the DI-out into the recording interface to obtain a balanced signal usually helps reduce hum, IME.
I have a preamp (B7K) with a 'parallel out' jack - something like that might allow you to drive both the amp and a recording interface simultaneously...
I didn't see any mention of input impedance for that device, which could affect the signal quality, especially the highs, especially if you have a passive bass. This is another reason why plugging into the computer sound card mic input is usually suboptimal - but it might be worth a try...
I'm at a loss to explain why your DI->XLR cable->interface method produced bad sound, although the Behringer's connector is labelled "mic preamp" so maybe it's not actually suitable for a DI-level signal, or again, the impedances are not well matched. In which case - I think I'd try plugging the instrument into either the 'mic Line In' or 'Line 2' jack.
"It's not supposed to be" this difficult - but I have no experience with your interface, so I really have no better suggestions than "try stuff" and read the manual...