As others have mentioned here, the KT88's are great tubes. I have run a quad of KT66, Quad of KT88's with KT77 as driver, a pair of KT 88 and GU50 as power with KT77 as drivers and many other combo's . They all offer a difference in sound, I personally liked the KT 88 and GU50 as power with KT77 the best out of these. I ran a quad of GU50's and that was very nice as well, but now running a six pack of GU50's, the biggest change I have seen (or heard!) is the increase in clarity. I no longer run the 6AS7 tubes or 6080, and sold my 5998's awhile ago. Great tube but preferred others more. The only 6080 type I still roll is the Aero Gold 5998A with the Aero Gold 6sn7's. As far as the way it looks, it is a personal thing. I like it, but others may not. I was an early adopter of the Elise, and the Euforia sn 0005, and rolled many combonations, but this AE version is just a step up the ladder from what I am hearing. Was it worth the extra to go from Euforia to the AE version? To me it was. I am happy with it, using the Senn 800 and Oppo PM1 phones. Will I continue to roll tubes? Probably, but I doubt if I will try new tubes, as I have so many tube combos already, I will try mixing and matching tubes that I already have. I have many excellent 6sn7 that I have not included in the mix, as well as other combos. I look at the tube cabinets and start to count the different combos and then go back and listen to more music, as the number of possible combos is getting quite large!