A riser shelf?
Pangea Audio Vulcan X Add-On Component Shelf or build a similar one out of wood.
ClosetMaid 3456 Large Shelf, White may not be wide enough.
DIY: TNT FleXy, Flexy Rack Thread. For a desk, make a single shelf version.
Single shelf Pangea Audio Vulcan X Add-On Component Shelf.
Audio Racks: 4 tier: Monolith, Mount-It! , Fitueyes.
I keep my recevier on an 18x18x18 Ikea like end table either under or off to the side of my desk.
You do want to be able to turn it on and adjust the volume so a mini amp would be best next to the turntable.
A receiver can be stacked underneath the turntable if there is an inch of space with the turntable feet or ideally under a shelf.
Or get a Turntable Stand or Crosley Soho Stand.
Or build your own DIY Flex Rack: The TNT FleXy Table - TNT-Audio • The Official <strong>Flexy Rack</strong> Thread • Easy Flexy Rack • made this modular stereo rack