I think you mean 'amp modeling', rather than presets. You cannot bypass your Valvetronix amp modelimg as it's a modelling amp, & that's what it does. But why would you want to? The Valvetronix modelling is infinitely superior to the V-amp modeling.
I think I've explained this over a hundred times before - a modelling amp & a modeling MFX unit do not mix, as you'll just get mush & noise because the amp models will conflict. If you want more effects with your Valvetronix use a non-modeling FX unit. If you want to run your modeling MFX unit through an amp, you need a 'straight' amp.
Rich

(PS - please post in the correct forum - I've moved this over to the correct AD15VT-XL forum

)
"I started out with nothing ...and I've still got most of it left!" (Seasick Steve)