Previously I ran the SDRPlay RSP1 via the IF-out (delivered by the RFSpace IF-2000, 10,55 Mhz). But there are a couple of disadvantages (switching pre-amp, att, etc. affects also the SDR, so you have always adjust the gain on the sdr too).
Luckily for most of the Yaesu FT’s (and for some Icom’s) there is an easy solution: I use now RX-in/RX-out from the FT-2000 in combination with a simple splitter. So I can now listen on SDR and FT-2000 independently via main antenna.
The SDR is connected to the RX ANT OUT of the FT-2000.
On activated RX-Button, this output has the signal from the antenna during receive. In order to feed both the FT-2000 and the SDR with signal, I use a Diamond SS500 splitter. The RX ANT OUT signal is split in two. Half of the signal is fed to the RX ANT IN and half of the signal is fed to the SDR. This way both radios have an identical copy of the signal.