I have a PDI-09. It's cheap and does what it's supposed to. You have to experiement a bit to get the sweet spot with your amp (the sound produced by the PDI-09 changes with the volume of the amp master and the settings on the device).
On my Shiva it sounds very good on the lowest setting with very low volume and in the bright setting, however when you turn the amp up, you need to go to normal or mellow and increase the dB padding.