I have a Providence Dual Bass Station, which I run with two basses, and it is a terrific piece of kit. It's 24 volt operation, so there's tons of headroom, 3 band eq with sweepable mids, mute, and tuner out. I much prefer it to the Tonebone I used to have, which I felt always sucked some tone out of the bass.
They are £300 in the UK, but I lucked into a new one from the US for £150 via eBay