Some years ago, I remember to have seen a way of disabling LNB Power in earlier DreamBox machines.
Since then, I've never seen it again in OpenPLi or DMM images satellite configuration menus.
In my home, I have several private dishes, but there is a "shared" one which gives everybody Astra's 19 East Vertical Low Band, band where spanish CANAL PLUS broadcasts its services.
Then people who subscribe, doesn't need to add a private dish to access C+ services.
It's a very commom setup in Spain.
With this setup, you don't need to send 14/18 V., because you'll always get the same band/polar. The common amplifier gives the 14 v. to the LNB.
So, is it possible to add another LNB type which sends 0 V. from input cable ?
Some other receivers (not enigma2) have an option to turn ON-OFF lnb power.