A quad LNB only has four outputs, and so you'll only have unrestricted channel choice for four tuners - and between two twin tuner PVRs and a single box, you have five tuners. (Assuming you are using twin tuner PVRs; little point these days in a single tuner one).
There are octo LNBs, which would give you eight outputs, so you'd have three spare. A quick bit of googling suggests a price of around 70-80 quid, compared to 25-30 for a quad.
However, if you do a bit of thinking, there are other solutions, depending on the equipment and how you use it.
First, if any of your boxes have an LNB out then you could piggy back one box on something else, depending on the layout of your home, and how you watch. For instance, main PVR in the living room, probably where most recording will be done - so give that two feeds direct from the dish.
You then have three things that need a feed, and only two feeds left.
If you'd unlikely to record often on the second PVR, then you might get away with putting just one feed into it - some will work like that. Or if the standalone receiver has an LNB out port, connect the standalone direct to the dish, and the output to the second tuner on the second PVR, with the first tuner on that PVR direct to the dish; you'll then be restricted in that you can only do dual recording on the second PVR when the standalone box is switched off. Or you could connect the standalone receiver to the LNB out from the second PVR's second tuner, and only be able to watch on that box when the second PVR isn't in use.
That's all a bit fiddly for wiring, of course.
Other alternatives - the 8 way LNB (and loads of cables coming through a hole in your wall), or a four way LNB, plus a multiswitch.
What's one of them? Remember back at the beginning, I explained there are four possible combinations of High/Low and Vertical/Horizontal for an LNB? There is a special type of LNB - usually called a Quatro rather than a Quad - that, instead of four independent outputs, has one for each of the four possible settings. You connect this to a multiswitch (which is a bit like an aerial amp for terrestrial), which has several outputs - again you need one output for each tuner, so at least five in your case.
The multiswitch then looks at what each tuner is requesting (high band, horizontal and so on) and connects that tuner to the appropriate signal from the LNB. So you only have four cables coming in, and can have lots of receivers. This is typically the way it's done in blocks of flats, but of course the multiswitches aren't that cheap; 5 in 8 out will be about 70 quid (the extra in is for a standard TV aerial, which it will distribute too).
You can see some examples
here
Nigel.
