That should work. As a test, you can try hooking the sub up to the tape out connection (and make sure that tape loop is set to record the source you are listening to). I have a Linn sub -- it should definitely work. If neither of those work, you might want to test your sub on another system. Any source with a pre-out should work.
Connecting Subwoofer to Linn Electronics
I have a Velodyne DLS3500R (active) subwoofer that I would like to connect to my Linn system (Wakonda Preamp and LK85 Amplifier). I've reviewed the manuals for the Wakonda, LK85, Velodyne and Sizmik (the Linn subwoofer), and it is not clear how to do this. I currently have Linn Keilidh speakers. Thanks in advance for any help.