This would require an entirely new range of Rossini, Vivaldi and future products. At least an extra transformer and headphone amp board inside the (or a) case, and the extra sockets, and output selector button, in the (a) front fascia. So this would not be available to current owners of these ranges.
Hence the idea I got (and others) for a standalone headphone amp, which, if there anyway is another box, could relatively easily be a preamp as well.
And then, with anyway another box, why not think/ dream about what it could contain more?
If you don’t want or need it: no problem. But if you do want a headphone amp into your Rossini or Vivaldi: they cannot retrofit it in.
The required extra transformer and the headphone amp board, with Expanse, already exist. Just a new extra case to put it in, no doubt some extra things I do not know about, and an extra opportunity to expand its capabilities, and there it is.