I just put 2 matched pairs in my VS55 and biased them to 65 and they sound great much better bass. Over all seemed to impart a greater sense of power. I had been using NOS tungsol 6550 and my first impressions are that the KT 120's sound as good in the highs and midrange and much better bass with my dynaudio excite 16 speakers only about 10 hours so far I would think that they need bait more time to break in
