I have a similar setup (http://www.stucki.com/krhen/music.htm, go to the GearList page, then my SCSI setup is in the middle column) and all works fine. The ESI4000 terminates regardless internally. I assume you've got a PC SCSI card since you've got your Jaz connected to it. Just hook'em up and turn on
1) Jaz
2) ESI4000
3) PC
When the PC starts looking for new devices PnP, and it'll tell you it finds eight unknown devices. Just DON'T cancel or it'll ask you each time. Just pick the UNKNOWN device item and there'll show eight UNKNOWN devices in your device list from then on, but no biggie. You can then use the Jaz from either the ESI OR the PC BUT DON'T let them both access at the same time. Also be SURE to get good (i.e. EXPENSIVE) SCSI cables. I learned that lesson the hard way. Once you have it hooked up and turned on, you can have the ESI search the SCSI bus with one of the menu options which I can't recall off hand. I've been using mine like this for a while, transferring samples with SoundForge and WaveSurgeon, without problems.