I use mine with a QSC PLX2402 and have great success. At this point you can get one of their lighter versions for a good price.
The F-1X already has that tubey tone built into it - it's based on the Fender Bassman circuit. You don't need a tube amp - this thing already does that.
You will need to bone up on what's available that works well for bass. Google it up and you'll find a lot of choices. This has been discussed at length in older threads here at TB.
Also keep this in mind - per Alembic, the flat setting for this preamp is Bass@2, Mid@10 and Treble@2 with Bright and Deep switches off. Is is basically a mid cut control, so to hear any mids it should be maxed. In addition, the controls do interact - each affects the others. Start at the flat setting and tweak to your liking. It does get a lot of sounds but extreme tones aren't what it's known for. The Deep and Bright switches help here though.
I love it for the solid muscular tone it can provide. Great preamp.
Yam BB Club #3; Lane Poor Club #5;
Haggy Bass Club #7; Warmoth Club #18;
Tele Bass Club #24; MM Sterling Club #25;
B.C. Rich Club #52; U.S Peavey Club #306; Sunn Ownwers Club #82