Hi...I have the origional Hurricanes. The only tubes I changed were the 6SN7's. I wrote a review about the amps and here is what I said about the 6SN7's. I have not (as yet) changed the KT88's except to replace bad tubes.
However, I believe the biggest fixes that occurred and solved most of the sensitivity/coolness problems I was hearing were two things.
1. I replaced the ASL supplied 6SN7 tubes with NOS Sylvania's from Andy's Vintage Tube Service.
The change in tubes was noticed immediately and continues to improve with use.
2. The KT 88's NEED TO BURN IN!!
I hope this helps!
However, I believe the biggest fixes that occurred and solved most of the sensitivity/coolness problems I was hearing were two things.
1. I replaced the ASL supplied 6SN7 tubes with NOS Sylvania's from Andy's Vintage Tube Service.
The change in tubes was noticed immediately and continues to improve with use.
2. The KT 88's NEED TO BURN IN!!
I hope this helps!