Sersalpha,
For what its worth I've been using a Promitheus Ref 4 with my DNA-1 monoblocks for about a year. It is a very satisfactory pairing to my ears and is well within your budget. It is much, much, better than the TLC-1 and Endler attenuators I used previously. I have not heard the C-core model, but that would also be comfortably below your $2K limit.
For what its worth I've been using a Promitheus Ref 4 with my DNA-1 monoblocks for about a year. It is a very satisfactory pairing to my ears and is well within your budget. It is much, much, better than the TLC-1 and Endler attenuators I used previously. I have not heard the C-core model, but that would also be comfortably below your $2K limit.