I am going to make a prediction based on my findings with my Lyr 3. . .KenRad VT-231 (staggered plates) is going to be the favorite tube of many. This tube does so many things right. The impact of the bass is the first thing of note, and will be the tube for the bassheads (me included). Next is the midrange, that is smooth without being to far back. The top end is extended with just a touch of air. This tube is slightly dark, but still has really good detail and is very euphonic. You can feel the music, and it is very engaging and fun. The soundstage is wide, and the overall imaging and impact is big and powerful, like live music. This is a fun tube and I think it will work well with a bunch of different headphones. My number 2 is the RCA VT-231 (grey glass, mica snubbers, 1940's). This tube has more mid bass, than the KenRad, and almost hits as hard as the KenRad. The midrange on the RCA, is a little further back, than the KenRad, and this really creates a deep, wide holographic soundstage. This tube is warm and smooth, with great impact and weight to the notes. I love a warm signature and this tube is king! The top end of the RCA, is a bit rolled off, and it does not have the air of the KenRad, but it could be the tube for a headphone with a hot top end. These 2 tubes are it for me, and I am buildling up my stock, so I don't have to worry about finding them, in the future. Happy listening!