Mr Peabody and Sherman in the way back machine...
I
think this has come up in the past with the request to separate the pre-amp and the power-amp and it wasn't possible due to intellectual property concerns. If people could separate the pre and post they could perform detailed analysis in such a way that would allow them to reverse engineer some of what's being done or something like that. I'm not sure the details but I remember something like that. If that's not, or no longer is, the case, or I'm just remembering this wrong, this would be a
very useful feature for routing as you say, so here's hoping!