Jeffrey, yes and no !
As far as I know, each "player" can only go to one device but if you have a suitable sound card it is possible to send two players to two different channel pairs and (say) the preview and cart players to a third. I have that setup working on a couple of systems.
The primary limitation is that PlayIt Live needs the sound device to present as multiple stereo channels.
If you have, say, a 5.1 or 7.1 channel sound card it can't currently map the channel players to the 5.1 (or 7.1) channels.
Since this is an obvious and desirable enhancement my guess is that the limitation lies in the audio library that PlayIt Live uses.
Earlier versions of PlayIt Live could be used with ASIO4ALL which could overcome this limitation but as I understand it, ASIO4ALL caused more issues than it solved so is currently disabled.
If your "Virtual ASIO cable" can be made to expose multiple stereo pairs then you stand a chance. If IN#3 presents as a separate audio device try that with a different player.
Another limitation of PlayIt Live compared to, say Mixxx, is that you send the players to a device. With Mixxx the channel players and the composite mix are all available to send to devices.
While Mixxx and PlayIt Live suit different applications you could experiment with Mixxx and VoiceMeeter Banana and see if that will present on separate mixer channels.
I'm not entirely clear what the headphone problem is, whether it is a balance against other sources of audio problem or just an absolute level issue.
If the latter then some sort of sound card with a volume control should do it. You also seem to be getting towards the limits of what is easy to do with a "soft" mixer.
Have a read of this:
about what a "hardware" mixer can do.
Is it possible to output PlayIt Live audio to two different audio devices at the same time? I am using a product called VoiceMeeter Banana. I am using its builtin "Insert Virtual ASIO" cable to send output from PlayIt Live to one of VoiceMeeter Banana's mixer hardware inputs (using the IN#2 Left/IN#2 Right portion of the cable). I want to be able to send the PlayIt Live output to another one of VoiceMeeter Banana's hardware inputs. VB Banana's "Insert Virtual ASIO" cable will let me do this by using the IN#3 Left/IN#3 Right portion of the cable. But, I need to tell PlayIt Live to send it to both the IN#2 and the IN#3. I thought I might be able to use Track Editing/Monitoring setting in PlayIt Live; but, it doesn't seem to work this way. Is there a plugin that I could use to accomplish this? Thank you.