This is surprising, since I thought Tech 21 has a separate DI box for Bass. Anyway check this out: https://www.virtualitystudios.com/Tri_AC_Incubus.mp3 Dunno from where I got his link, but the bass is via Tri-AC directly to mixer. Anyway, that reminds me I had to show to doubleclick: why Tri-ac is better into line-in of guitar amp, than guitar-in.
Well, theres a link on the Tri AC page which has some soundclips of a bass through it. And I wanted to hear the difference bet the two ie. guitar in and line in.