Is the PXI-4498 capable of sampling a waveform from a pure voltage source if the IEPE power is turned off for that channel? For example, if a waveform is output by a cd player, can the PXI-4498 sample this data as long as the voltage does not go over the voltage range set by the card? If this is possible, are there any other setup options required besides turning off the IEPE power to that channel?
The 4498 has software selectable IEPE excitation. You can elect to disable it for your analog input. You should be able to sample the voltage output from your CD player as long as the voltage is with in the analog input voltage range of the 4498. Here is a link to the 4498 specifications. Are you having any difficulties sampling this voltage?