Can anyone help me to clarify the relative gain values for the 12**7 type tubes? I know that various iterations have X% less gain than the 12AX7, but it'd be nice to have a reference, or a scale, showing the relative gain values for 12AX7, 7025 (same 12AX7, right?), 5751, 12AU7, 12AT7, etc. I've seen varying figures from varying sources, and I'd like to straighten this out. Thanks, Tom.