Terrific review. Well written, easy to follow and understand, and very informative.
It's interesting that your Impacts are similarly positioned as my Double Impacts are, and in similar sized room.
I also agree on the flexibility of amp pairings. It's great that you are using a higher powered amplifier. There has been a lot of discussion vis a vis the DIs, at least, with very low powered amps...good to see a happy pairing and recommendation with higher power output tubes.
Looking forward to hearing more about your journey with your Impact Monitors.