Probably not. You use a DI box to go from high impedance guitar signal to a low impedance line or mixer input. Assuming your levels are OK, no worry.
@nickrose: By guitar preamp, I mean the TS 1/4″ instrument input of a guitar amp that has an FX loop. Such input is high impedance, so if I want to use a H9K FXChain like say compressor or flanger, and put it in front of the preamp, then the signal, whihc coming from the H9K is low Z, would need to be transformed (pun intended) to hihg Z, whihc as far as I know can only be done by a reamp box. I am wondering how @rvickers does that?