Just my two cents regarding the Freya. Let me preface this by saying I am a Schiit fan, have a Gungir MB, Loki, and Mani in my main system and a Vali2 and Modi2 on my desktop. I tried the Freya as a replacement for my Adcom GFP-750 and found it to have a distinct veil. I am not positive it wasn't defective, but when I returned it to Schiit, they never informed me that there was an issue when they tested it (which they supposedly do on all returns).
I ran the Vidar while my amp was being rebuilt and it was a great amp, the only issue I had was not enough power for my Magnepans (plenty for Revels). I am not sure that the Rangarok would be an upgrade from your Krell, or enough power. If I were looking at a replacement, I would probably be looking further up the ladder, but it will cost you dearly, something like a Pass or ?????