I`m a mobile DJ and have to carry very heavy equipment. Since my storage is on -1 floor (with no elevator), my wife was so nice to buy me this cart as a present.It worth the money big time!Now I`ll explain why - first of all, the fact that I can carry heavy speakers on it and easily carry it on the stairs - that the big YES for this cart.Second, the bottom of the cart is big enough to put big speakers without any concern that it will fall (it even arrived with the rope that can tie the speaker to the cart).It is not a lightweight cart, and I like it. I haven`t tested it with 330lbs but it seems like it can carry much of weight. It is very sturdy and strong.It has 2 extra wheels in case some wheels will break.I love this cart and now I love my wife even more!