Hydor Vs. Eheim Vs. Via AquaSound Wise
 

I have heard an Eheim 1048 running and it was quiet. But there so damn expensive and rather large. I'm purchasing a Lian Li PC-62 its the extended PC-60 so i should have room for either. I just haven't heard a Hydor L30 and from the pump curves on this board it looks like it would be a smart idea for a inline inhouse watercooling project. The Via Aqua 1300 also looks quite apealing for cost but i have no clue on its size or shape i also see that they sell a 2600 which is a more powerful 740gph i am running a 500gph pump right now and going down in power does't sound very apealing while going up does :). My current setup is an External acrylic box holding my watercooling setup run to my thermaltake xaser 2.

I personally find the Eheim 1048 to be a little quieter than the L20 in side by side comparison. The L30 and Eheim1250 are nowhere near as quiet as either.

The L20 is super tiny though. If space is an issue go with it. The noise level isnt a huge difference; I dont even know if you could tell between them if they were in a case.

http://www.procooling.com/~phaestus/l20vs1048.jpg

Never touched a viaaqua so can't comment.