I will hit the 125 hour mark this evening. So far the changes I have noticed follow the other break-in threads here on AC. Mids and highs are getting more precise every day. Bass is as good as I have ever experienced, and overall detail retrieval is stunning! I'm running the Bass Gain at about 85% and it blends nicely.
At the very beginning, I was worried that the X-5 pairing with the AGD Audion Mono Blocks might be too much of a good thing. No longer! What was pinched and dry (highs especially) has opened up very nicely. Again, I am stunned, and very, very happy!