Your better to use the Aegir on the mids and highs and the Vidar on the bass and if they are different gains use a Schiit Sys on the louder of the amps to reduce it to the others level then use your Schiit Freya + preamp as the master still.
That’s a really bad idea. Particularly for a Vandersteen which has been phase aligned with such care in it’s design.
You should vertically bi-amp with 2 identical amps. If you doubt me just give Vandersteen a call. They're happy to talk to customers about such issues.