I have a lumatek digital ballast(switchable). I tried to put one of my 400w MH bulbs in the socket and it doesn't fit.. my question is, if I buy a regular 400w MH magnetic ballast and socket, will my bulbs fit? I don't want to use the ballasts they came with. Also, why do magnetic ballasts seem so much more expensive than the digital? What's a very good magnetic ballast company? I want a 600w HPS, and a 250w, 400w MH. Thanks in advance for any help. PEACE