🚀 go-pugleaf

I wouldn't recommend a 3dB splitter before either preamp.
If you do this, you are automatically degrading the system
noise figure by the 3dB loss of the splitter- same as if you had
3dB of cable loss between the antenna and the preamp.

I believe the answer is to build (or purchase) a wider 
bandwidth preamp. Avantek has an application note describing
a GaAsFET preamp with about a 0.4dB NF and about 20dB gain
which has an untuned input (matched to 50 ohms) using the
ATF10135 device and which will have excellent performance
over AT LEAST 100 MHz. Check it out. 

Put the preamp as close as possible to the antenna and
then run about as much coax down to the receiver as you want-
you'll have plenty of excess gain. This eliminates all the
splitters and combiners. In fact you could put a splitter
after the preamp and use it to drive a couple of receivers
and still have enough gain for both.

Hope this helps.              73    Dave     KD5RO