The maximum voltage between channel slots is 2 Vpp and is not possible to change since this is determined by the FPGA itself. It is possible to generate up to the 10 Vpp max voltage on the Moku:Pro outputs by changing the gain of the desired output to +14 dB in the MiM configuration screen. For more information on the difference between the max Vpp displayed in the WG app, please see this forum post here.