The kt 77s bettered the kt120s in just two areas, upper end extension, and depth. The kt120s were better in every other way in my system. I am running Revel speakers, which are known to be power hogs, and that very well could account for what I am hearing, and why I like the kt120s better.
kt77 vrs kt120 in Rogue M180s
I recently was a able to compare gold lion kt 77s verses tung sol kt120s in my Rogue audio M180 mono-blocks, and wanted to share my experiences with you. I did these comparisons over a period of weeks, so I think I now have a pretty good understanding of their sound in my amps. The kt77s have a little bit more air and extension in the treble, nice midrange, and very good depth, and slightly looser on the bass. The kt 120s, were clear and very open sounding, with better projection into the room with the sound stage, with less depth than the kt77, but have better width and separation. The kt120s also had better Bass extension and control over my Revel f32s woofers, They seemed to wake up the speaker, everything sounded dynamic and full. Besides the little bit of roll off in the highs, I much preferred the kt 120s in my system. Hope this helps some of you, Christopher