Replacing a pretty good DAC with a slightly better DAC seems like throwing good money after bad. The Node 2 has a pretty decent DAC (with the qualifier "for the money").
The only thing that jumps to mind for me close to your price range is the Schiit Bifrost 2. You could probably find a used one in your budget. Better than the DAC in the Node 2, but it won't provide a dramatic increase in sound quality. The Bifrost will have more detail and be a little "warmer".
Sell the Node 2 and see if you can find a used TEAC NT-505.
The only thing that jumps to mind for me close to your price range is the Schiit Bifrost 2. You could probably find a used one in your budget. Better than the DAC in the Node 2, but it won't provide a dramatic increase in sound quality. The Bifrost will have more detail and be a little "warmer".
Sell the Node 2 and see if you can find a used TEAC NT-505.