A-138m is a pretty brilliant module IMHO, at least with Euro level signals. It’s not the quietest one out there though and there can be some crosstalk/bleed.
Not sure how it would behave with line level signals in general – it might be a bit noisy, or the knob response might feel a bit weird.
I’ve used it to attenuate Euro signals for pedals while also patching feedback back to the pedal, and then run it from there to my audio interface (without going through more Euro modules) and it was fine for that. But that was Dark World with an intentionally noisy/degraded sound, so I’m not sure that’s a useful anecdote 