PS Audio transport/DAC: new clock?

Currently, I own a PS Audio Lambda 2SE transport, combined with a PS Audio SL3 DAC (via AES/EBU). Someone suggested it would be worthwile to get a new clock installed. Would that bring any benefits? And which clock should I have replaced? The one in the DAC, in the transport, or both? Or shouldn't I bother and buy some cd's instead?