Good Copper IC's for 2.5M RCA pre to amp?

The big problem you have is the long length combined with RCA connections (signal loss). 1m or less reduces the problems. So if at all possible, reconfigure your components to accomodate shorter cables.

Synergistic Research Resolution Ref x2 active. I went to the RR x2 instead of the Venustas and several others for the body, imaging, midrange, and bottom end they possess.

You'll save some money in the process. other than the RR's I'd say try the SX Ltd. from Nirvana, above the SX's I'd say the Acoustic Ref active, also from SR. The SX's are the imaging champ of the lot however. Their ambient retreval is flat out scary.

Thanks guys so far.
Tweak1: Not sure how much signal loss is associated with a 3M run, but Vladamir at Lamm did not think that would be any problem with the LL2, and it certainly was not a problem with the CAT Ult MkII or my Lector Zoe. I am running from a cabinet to monoblocks positioned between the speakers, so 2.5M is my minimum, and I would not want to go over 3M. Unfortunately, virtually none of the tube preamps I have liked have single-ended outputs, since with my new Lector Digidrive/Digicode, I could run a fully balanced system if I found the right preamp.
Blindjim: I will look into those you mentioned, although I have no experience with either Synergistic Research or Nirvana.

Any decent preamp will drive a pair of 2M or 3M unbalanced cables easily and without loss of detail.

The post stating the contrary is simply incorrect.

I agree with Audiofeil. Any good IC, I have the Cobalt Cable ones currently but have used Kimber and many others, will make that run without problems. This assumes a good match between the pre-amp and amp concerning impedance.