Is it possible to connect the G-Force to an amp that doesn't have any effects loop?
Yes, if you plug your guitar directly in the G-Force, and connect the G-Force output to your amps line input.
This is possible because the inputs on the G-Force are capable of handling a high-impedance input.
However, we strongly recommend, that your source of distortion/overdrive is placed before the G-Force in the chain, as many of the effects in the G-Force will sound funny, when being fed a distorted signal.
In other words, if you use your preamp for distortion, you'll need an effects loop, to make the most of the G-force's effects.