Humax and Single LNB
Having since had a quick look at an online Humax User Guide (page16), it seems you can achieve the same without the need for a splitter.
Humax have included 2 inputs and 1 output on their PVR receiver, which means that with the correct set up you can at least record one channel whilst watching another, providing it’s sharing the same polarity.
All you need to do is connect up your cable from the satellite dish to input 1, then using a small length of cable with F-plugs on both ends, connect up input 2 to output 1.
Sounds handy for an existing single LNB set-up.