i just got an omega bass tube that has an amp on it and rca input. but
im not sure how to connect my rfx9210 to the bass tube. which wires do
i need to connect the 2?

you do not hook an amplified bass tube up to a amplifier, that is why
they are already amplified. (duh?)

you hook it up via the RCA's coming off of the back of you headunit,
non fading if applicable ( that way you would have a way to control the
volume), but there are many different ways that you can hook it up.

if you already have an amplifier installed in your ride - and it has
outputs on it as well - you can run a set of RCA's from the output on
your exsisting amp to the RCA's on the bass tube.

or you may hook it up to the rear RCA outputs on your headunit, or the
front outputs if you wanted. and you could use the fadewr as a make
shift way of controling the volume.

or you could buy a line level adapter and hook it up to your headunits
speaker output wires - and then plug a set of RCA's into the line level
adapter to the bass tube.

see...there are many ways this can be achieved.

but you don't hook an amplifier up to a amplified bass tube, hence the
wording "amplified tube"

WHO SAID ANYTHING ABOUT AN AMP? NOT ME! HOW DO I CONNECT THE
POWER/GROUND TO THE TUBE?

run a power wire from the battery to where the tube is, and hook it up
to where ever the power goes to the tube,and a ground wire ground from
the tube to something on the car that is metal, like even a seat bolt
or something if you do not want to drill any holes into the car, this
should suffice, not very professional, but it'll work well.