You could introduce some noise by mounting a power supply inside of the SCXI chassis. The chassis itself does provide some degree of shielding, so you would be eliminating some of that shielding by placing that power supply inside. However, we have no specs for that because the chassis was not designed for that application. Another option may be to use the SCXI-1124 analog output module. While it has 6 channels with a +/- 10V range, you can cascade channels to get up to 60V per module. Below is the link to the SCXI-1124 produce page. I hope this information helps.
SCXI-1124