I need help on a 12 tube phantom. The tubes check good. We have found some socket ground issues and have been going through it. We are only seeing about 700w out of it and the tubes test very strong. It is a 4 driving 8 configuration. My question is how much output power should these amps produce? Having 2 more tubes will they outperform the 10 tuber that came later? How much drive should you drive an amp like this. We are driving it presently with about 10w of swing. Im not into hooking modulators up to these sweep tube boxes. I want to use it as it was intended. Can someone help. The relays all seem to be working. Is it true that the 10 tuber produced just as much power but was more efficient. Can someone that knows these amps help me. I would really appreciate it.