nope - because there was like here Swapped my RPi3 for a pi0W and destroyed my range! [SOLVED] - #6 by TomMuc nearly zero to document. of course i saw minimal decrease in messagerate (maybe 1-2%) as the both dongles feed back a little noise. but the -3,2 db the splitter reduces signal-strength behind the +15db the lna amplifies is not worth to mention. it’s nearly all about snr and that stays easily good enough for mode-s.
but you can see the statistics here: http://flightaware.com/adsb/stats/user/TomMuc#stats-60978
splitter was installed today 27. sept. 2017 10:00-11:00 mesz (08:00-09:00 utc) and did some reboots over the day