So, consider that FX1 needs some power amp companion. They can be tube or solid state. Tube are great for tone since they can sound very clean but also can be overdriven to give us the beneffit of harmonic enhancement and some kind of compression. The "problem" is tube amps usually not excell 200 Watts power, while you can get thousands with a solid state amp.
This is a important choice to make, because solid state amps have the power but some may lack those tone qualities at different degrees (some FET amps can react similar but how close is controversial). For live acts at large venues it may be obligatory, though.
Another thing to consider is distortion since we are talking about the Ox and the FX1 is more on the clean side of the tube spectrum (as far I recolect, I don't own one). So I imagine you'll have to get a device to distort the bass signal or to push FX1 tubes into overdrive, like a pedal before.
And here is where I stop because distorted tones are very personal, there are several ways to get it (fuzz, distortion, overdrives, boosters, preamps and even power amps) and they tend to kill lows (that is why bass pedals enables to mix the dry signal to the processed). Chris Squire and Geddy Lee used Rick's individual PU outputs to send the bridge pickup to a guitar amp while sending the neck one to a bass amp, to get the drive with no low end loss. With the FX1 you can try distort only the highs sending them to the Orange, you just need to know if the crossover output matches the OB1 preamp input, since it may be too hot and the Orange doesn't has independent power amp input (in fact, that model have solid state power amp so you couldn't beneffit from its preamp overdriven tube tone, anyway), but you can use the double output your bass has, too. You just need a Y cable.
