First I have to thank you guys for sharing your knowledge. I initially came to this forum to ask about the possibility of converting my two MC275's voltage from 120V to 240V. Lots of members chipped in and told me that it's an easy thing to do - all I need to do is to switch a few tabs on the primary wirings of the transformer. So I paid an electrician with over 20 years of experience of hi-fi repair to do the switch for me. He told me that he switched a few tabs of the primary wirings, and then tested his work by putting 220V through the primary wiring and then measure the output of the secondary wiring. Everything was looking good. After I took the amp home, I went to Radioshack and bought some 2A fast-blow fuses. I switched out the original fuse which has a 4A rating (I don't know whether it's fast-blow or slow-blow) But when I tried to start the amp by giving it 220V, the 2A fast-blow fuse blew immediately. A friend of mine told me that I shouldn't use a fast-blow fuse because the initial current surge would definitely blow it right away. Does anyone know which fuse type is the right one to use? I must admit that the original 4A fuse supplied by Mac looks just like a fast-blow fuse. The slow-blow fuses I saw at Radioshack all have slightly thicker filaments. But my friends say some slow-blow fuse filaments are just as thin and it is difficult to tell the difference.