The lifetime warranty comes with the amp because All markbass comes with a warranty through the company. Only problem is you gotta pay for shipping to italy. However if you buy through GC then they will fix the amp right there. So it saves having to ship your amp to Italy to get fixed.
This info is very, very wrong. The Warranty you get with your Markbass Product is through Guitar Center themselves, or should I say a warranty firm that they have contracted. Guitar Center doesn't fix the amp, the amp is sent to a repair shop on the east coast that is contracted and liscenced to do the repairs for markbass. This has all been widely covered and documented here on talkbass.
edit: I believe this is the thread that details someone's actual experience with dealing with the warranty: http://www.talkbass.com/forum/showthread.php?t=366996
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