I'm planning a 2 x 4-400A amp. I wonder if it would be possible to connect the filaments in series and use a 10v 15a transformer? If I do this, I guess the DC return would be the common point where the filaments are connected to each other. Is that correct? Are there reasons that this would be a bad idea? -- Vic, K2VCO Fresno CA http://www.qsl.net/k2vco/