Balanced & unbalanced line out-input confusion with Audio Interface and pre-amp

[Oqlanth]

I recently got Boss BB-1X digital pedal which has balanced TRS line out. I try to use it with my Behringer umc204hd which has two combo XLR-TRS inputs with gain control and pad and inst/line buttons for each input.

When I connect my pedal from pedal's balanced TRS line out to the sound card's combo input with balanced XLR connection, the sound card gains sound from my bass even I totally cut gain of the soundcard's input. The inst/line button becomes ineffective. I also tried it with unbalanced TS (also from pedal's balanced TRS line out) to soundcard's combo input with XLR, similar situation happened...

Both outputs of the pedal have -20dbu level but balanced TRS line out got 600Ω and other one got 1kΩ.

The manual of pedal says:
"The LINE OUT jack provides a balanced output that preserves the tonal character of the bass amp. This is convenient when connecting a mixer or recorder." Frankly, I didn't notice any tonal character difference when I connected it with unbalanced XLR. Or I am doing everything wrong and still couldn't connect it via a balanced connection?

I don't understand what happened exactly? Is this sound card's reaction for XLR connection which is unrelated with balanced line out (in case of ineffective ins/line button, and high gain from input)? Will it react similar if I connect pedal with sound card balanced TRS input? Right now, I don't know if it is connected balanced or not because it gave similar reaction to both balanced and unbalanced connections. How can I understand if it is connected balanced?

 

[byacey]

Balanced line is for long signal runs, and is superior to unbalanced for rejecting noise. with your input trim all the way down on the sound cards preamp, it should still pass signal, as this is the lowest gain setting, not muted like a typical volume control. You shouldn't really notice any difference in tone quality, except for perhaps a lower noise floor on a longer cable.

 

[Oqlanth]

Balanced line is for long signal runs, and is superior to unbalanced for rejecting noise. with your input trim all the way down on the sound cards preamp, it should still pass signal, as this is the lowest gain setting, not muted like a typical volume control. You shouldn't really notice any difference in tone quality, except for perhaps a lower noise floor on a longer cable.

Thank you very much., I got it better now. So I should not behave to the sound card's gain like it is 'normal' unbalanced connection (signal); i usually need half amount of gain to achieve unclipped sound compared to 'normal' unbalanced connection....

Thanks again for answer and information.