While recording a vocal track it dawned on me that some harmonies would be great. I have a terrific vocal harmonizer (hardware), namely the TChelicon Harmony-G XT, which works with a guitar input for determining the harmonies in real time.
I recorded a few chords with the keyboard and a guitar VSTI that follow the melody chords into the DAW (no need to record actual guitar) and assigned them to an output bus. Both tracks can be deleted after the vocal harmonies are successfully recorded.
The output bus plays through an unused output of my rec/pb hardware (Focusrite Saffire) which is not connected to any of the mixes that go to either monitors or headphones. (On the Saffire, you have to assign one of the DAW inputs other than DAW1/2[which is the monitor speakers] to the output used).
During recording, I hear a zero latency mix from the hardware (the Saffire can do that), including harmony vocals and DAW, and the harmonizer only "hears" the fake guitar chords for determining the harmonies.
Be aware that the output signal from the DAW is very strong for a guitar input, so be conservative on the volume settings.
The result is excellent, great boost to the song.
This procedure can be used for other types of reamping, provided you have hardware that has extra output channels.
You may even go as far as reamping the voice track itself
along with the fake guitar chords. You could thus force different harmonies if you alter the chords into, say, dominant sevenths or whatever. However, if you sing in the harmonies kinda "live" as described above, you most certainly sing differently, having Linda and this hunk of a black guy singing along with you.