The Pimeta does implement a virtual ground with an opamp, the TLE2426, only more compactly packed. For headphone drivers it's a simpler powering system, certainly better than using two batteries in portables, using the mid junction as ground. Those batteries may discharge differently and cause power unbalances. The other way is to use a DC-DC supply to generate the +/- voltages. Using the TLE is a simpler way to do that that may work on such circumstances. The additional circuit for the ground amplifiers allows more current to be used, which is the limitation of the TLE and essential for hungry headphones. Balancing a signal can be interesting, particularly if the grounding can't be kept absolutely zero. You could use a balancing chip to feed the separate drivers with more isolation, or a transformer. But of course, you would need to recable the headphones. But most quality headphones that I know of already have two-wires for each driver, that only get together on the connector. There wouldn't be any-rewiring.