I got a 600W Malibu low voltage transformer powering my landscape
lights. But some of the lights further from the transformer are not as
bright. I only have a single 12 gauge wire with all the lights
attached on it.

Can I attach another 300W transformer at the far end of the wire so
that the lights there will be brighter?

I cannot really run another wire from the 600W transformer, since much
of the wire run under concrete pathways and also my driveway.

Thanks