The stand came with additional metal supports which you can place between the top and bottom shelf but even if the 5500.2HC sitting on top its not causing the top to bend at all, probably due to the weight being distributed over most of the surface area and not just in the middle.

Hifi - PC, 861, 2x505, XTZ
Cans - PC, Oppo HA-1, Fostex TH-X00PH