No, the Erica LINK is just fine for this purpose. Go ahead and use that. But keep in mind that it's just a passive attenuator bank, so you still need to control your levels carefully on the modular side of it, as it can still output something relatively hot if you hit it really hard on the modular side.
One other thing to remember, also...this is likely to be a simple resistive circuit and this means that it can pass DC. That's Garfield's concern here, since your interface can also pass DC. The best solution, eventually, will be to exchange the LINK module with something that has transformer balancing/isolation, which prevents the DC from going beyond the transformer itself. There's another method of preventing DC from passing, though...but I can't look at the PCB side of the LINK module or find any data on Erica's site that says whether or not the attenuated outputs have capacitors that work as DC stops. Not quite as preferable as transformer isolation, but still quite workable.