Help with a new Tube headphone amp blowing fuses

Received a new headphone amp this week to replace one from same manufacturer that is still serving me well but wanted to try a little more power, new amp 1.4 watts versus a .35 watt on the older one. Have about 25 hours on new amp and turned it on this morn loaded CD and after about a minute the music was replaced with an elevated fuzzy noise right before fuse blew, replaced fuse and it blew a second or two after turning unit on, saw nothing unusual going on with the tube glow, replaced New amp with the older amp in system and all is well. What are the possibilities of fault here, would like to handle myself without having to send back to Japan for warranty work.