Short answer - No, you should not.  You may damage your NU Audio Pro card(s) and/or the device you connect to it.

Although the NU Audio Pro Cards can be connected to each other by using a standard mini-DisplayPort cable, these cards use a custom mini-DisplayPort connector pinout in order to communicate with each other and transfer power.  As a result, plugging any third-party or non-compatible device to the NU Audio Pro or NU Audio Pro Surround cards may cause irreparable and permanent damage to the NU Audio Pro cards and/or your third-party or non-compatible device.

Please also keep in mind that although the mini-DisplayPort cable included with the NU Audio Pro 7.1 cards and NU Audio Pro Surround card can be replaced with a standard mini-DisplayPort to mini-DisplayPort cable, the cable included with those cards was extensively tested and chosen to provide the best performance with the NU Audio Pro for multi-channel analog surround.  If you replace the cable and begin suffering poor performance or audio artifacting, please test again using the stock cable.