The preamp will compensate for the losses in splitting the signal. If you still can't get WPXI, then you will need to add a low-VHF antenna to your system.
John, at
RabbitEars, you will note that there are precious few full-power stations in 2-6, with only 8 nationwide on 6. There are at least 30 stations on each on virtually all channels from 7 on up.