Best DAC for my system?

Thinking I would like to add an outboard DAC to my system.  I have Forte IIIs, McIntosh MC2105, McIntosh MX119 and I use a Bluesound Node2 for streaming.  What would be best options in the $500 range?  Or do I need to spend more on the DAC to make enough improvement over the Node2 DAC?  Thanks....