The answer to the speaker question is on Page 12 of the user manual.
http://www.egnateramps.com/manuals/Tweaker40.pdf
As far as the fuse and tubes go. Does the amp power on (jewel light lit)? Did you have a speaker load connected when the fuse blew? How did you know the fuse blew? There is a description on Page 11 on how to replace the fuse. Pull it out and take a look at it. I'd replace the fuse and try again before buying new tubes. Buy 4 or 5 fuses while you are at it. Also make sure all of your tubes are seated (pushed) all the way in and visually watch them the next time you power up. If one or both get super bright then shut off amp immediately.
Is this a new amp or a used amp?
Hope that helps. Hi.Well thanks for the reply.I was just playin the Amp with the new Cab attached ,low volume,low gain and after 10 minutes or so the whole thing shut down.Amp didn't feel hot or anything.Just shut down and won't power up. It's used Amp got it from GC used section with one year warranty. Thanks
PS: Never owned a Tweaker and I'm not an amp tech FYI.