Is it ok if I use KT-66 or EL34 with Mini Torii?

I tried using VA 350B, very good improvement in tone and balance vs 6l6. But the distortion is still a bit high when play complex orchestra. Looking for some good tube in KT-66 or EL34.

I know for Groove Tube, there is rating system. I'd like to see if I can buy rating 8-10, low distortion tube to try.  But not sure should try their 6L6 tube ( a few different versions), EL34 or KT66.

Barry