There is no change to the sound or gain. The 2 dB difference in dynamic range essentially means that the G30 has 2 dB more noise than the G50. But that noise is 118 dB lower than the maximum signal.
A couple of examples ...
A CD has a dynamic range of 96 dB
Typical guitar amps have between 75-95 dB of dynamic range
Likewise the difference in connectors is simply locking or not. No change to the sound.