Not really. You'd need to plug it in and apply a load in order to measure the current. If you're lucky you might be able to find a review if it's a name brand supply, but if it's an off brand, forget about it. Plus the supply you buy may be of a different build quality anyways. Either make sure they have a return policy that will allow you to return it (just say it wasn't powerful enough for your system) or size it appropriately for your desired load plus a healthy margin of error.
