Why it won't work? I don't find any problem in using a 50W cab with any amp out there. I've pretty much always used a 50W cab with all my amps, be they 100W or whatever. They sound much better, too, than something with too much wattage. I think the ears will tell you it's getting too loud way before you blow it up...
Dee
"When life's a biatch, be a horny dog"
Amps: Marshall JVM 410H w/ Plexi Cap mod, Choke Mod & Negative Feedback Removal mod, 4x12", Behringer GMX110, Amplitube 3/StealthPedal
Half a dozen custom built/bastardized guitars all with EMG's, mostly 85's, Ibanez Artwood acoustic & Yamaha SGR bass, Epiphone Prophecy SG, Vox Wah, Pitchblack tuner plus assorted pedals, rack gear etc. for home studio use.