well regulated, high current DC power supply using a modified PC power supply that isn't otherwise being used. Plus, the idea of using tubes with 5V filaments instead of 6.3/12.6V reduces the competition with typical audio tube customers and makes the use of a high-current 5VDC supply possible. For a few bucks, you could get a 5 Volt transformer with a decent current rating of 10 Amps, and not have to worry about the number of tubes you need to feed for a while. Filament transformers come in many voltages other than 6.3.