Shunyata 8 & 6 any difference in sound ?

Has anybody tried back to back test ?
Yes, The 8 has a more air, slightly softer presentation. Great space and very coherent. The 6, 4, 2 are more direct, maybe even a little more neutral with a slightly more forward soundstage. Analogy might be 8 (tubes) 6,4,2 solid state. I have the 8 and love it (all BAT gear)