I agree with Harvey - you have classic symptoms of a worn high clutch. You're going to need a rebuilt. Try solenoids and coolers if you want, but you're going to be rebuilding it just the same.
56k miles is pretty early, but that's the SVX for you. When you do put a rebuilt tranny in (and I predict that that's what you're headed for), put in an aftermarket cooler. The SVX's tranny is fine - it's not 'weak' or 'problematic.' It was just not provided with sufficient cooling by Subaru.
Sorry, but I think a rebuild is the only thing you're in for.
