The cheapest way to experience crossfeed is to plug your headphone to a Hometheatre receiver, switch between Stereo and then DTS or 5.1 (or something).
At least when I use for watching movie, I prefer 5.1 setting 90% of the time.
It brings the scene in front of you, close to Cinema experience while Stereo is more Left and Right experience.
I can't say much for music as my receiver is not audiophile enough so I never listen music from them.
For now, I am still happy with my 2 channel headphone amp, I never try a good crossfeed like Phonitor at home so I can't comment much on this.
Worth it? try with receiver first see if it worth $600 for you.
The Phonitor is not a DSP gimmick, is all about analog... maybe this video will help you understand better.