Try Optimum (
www.optimum2000.com) their racks are modular, and you can choose your own shelf heights. The offer rods from 80mm up to 600mm.
The 200mm rods would meet your amp requirements, and the stand is 1.1M wide and 500mm deep.
I've just bought one .... see my Optimum Thread.
OK this is an AV rack ... but I'm sure their HiFi racks are just as modular.