The requirements for the Lock In Amplifier are contained within the document linked bellow. The S series can be used with the Lock In Amplifier but not the E-series.
http://ae.natinst.com/operations/ae/public.nsf/fca7838c4500dc10862567a100753500/ebaadbd271adfec586256c86007b63f9?OpenDocument
Regards
Jon Bowers
Applications Engineer
NIUK