I was looking at how these 2 tubes compare. I have always used a 5Y3 but I was looking at an amp that calls for a GZ34. It has 3 12ax7's and 2 6V6's. Nothing a 5Y3 can't handle. So what does a GZ34 provide that 5Y3 doesn't. I searched around a bit but could not decipher the explanations.