because my B2 setup doesn't play music, but works fine without the teleporters.

-there are no crossed cables
-the right 3 data/clock connections are in place
- i use standard cat 5 no crosscable
- power to teleporters is about 6V, onboard regs +\- 3,3V
- a gnd connection is made on the receiver side to metronome
- i tried several earth to gnd connections and gnd directly from cdpro to gnd B2
- dac and chassis have floating earth

I already bought a new pair of teleporters, in case the others are down, but don't want to damage the new ones.

In your first picture, it looks like you are only sending one side of the LVDS signal over the CAT5 cable.

The B row. the output of the Teleporter is an LVDS signal for each channel. As a differential signal, you need two halves (+ and -). You need to connect each twisted pair of the Cat5 to the A/B pairs of outputs. Without that, the receiver is not receiving an LVDS signal, and won't be able to reconstruct the single ended I2S data.

Well, the odea is you keep the I2S lines as short as possible, and add needed length to the Cat5 cable instead. :)

Excellent! :)