Power amp around $3000 for C-J Classic preamp

Musical Fidelity 308 would be one, I have used several of their units. Parasound A21 [the 250 watt stereo] has a good rep. These are both way under your limit. There are just too many possibilities, especially since the speakers are uncertain. Unlike the previous poster I very rarely use the same make amp and pre amp, I think the last time was around 1990 except for integrated amps. When I do it is more by coincidence than planing; when you read reviews of an amp and preamp almost invariably one will be regarded as the star of the combination. The CJ should work with a wide variety of amps, decide on speakers first and then pick an amp that will drive them well. While it is true that manufactures make their units in combination you may or may not like the sound they were striving for. In my long ago days as a Krell dealer I liked their amps considerably better than their preamps; I have thought seriously about getting a Pass Labs pre, but don't want to deal with Class A amps again. I think if you look at members systems you will see many if not most have mixed marriages in their electronics.

Whatever amp you choose, be aware of the input impedance and the CJ preamp's output impedance. Choose wisely.

Not only are like brands of amplifiers and preamps designed to work well together sonically they are also designed to work well electrically and I have heard plenty of bad matches.
If you don't mind the process of buying and selling while you mix and match until you get it right or if you have several amps and preamps on hand to try together, your safest bet is to stay with the same brand.
I agree with Stanwal, CJ preamps are one of the easier to match with, say, a solid state amplifer, but you don't have a CJ yet and you may end up with something else.
The Quicksilver full function preamp works especially well with a variety of amplifiers because of it's extremely low output impedance.
But unless you have a ton of stereo equipment lying around as I do from my days as a stereo dealer and collecting choice items over the years as a hobbiest, then you may want to stick with the same brand.
Keep in mind many solid state preamps often take up to 3 days before sounding their best, such as Krell, Mark Levinson, Threshold and Audio Research solid state and hybrid preamps.

Foster_9, That is very good advice.

I have posted this before because it is a good example.

Several years ago when the Audio Research LS-2 was new, Stereophile reviewers were using it as their reference preamp. Don't ask me why. I never warmed up to the LS-2. During that time there were two new mid-priced solid state amplifiers on the market. One was the McCormack DNA-1 and the other was the Parasound HCA-2200.

The Stereophile reviewer reviewed these two amplifiers using the Audio Research LS-2 preamp and gave the DNA-1 a glowing review while he literally trashed the Parasound amp.

I had both the LS-2 and the Parasound amp on hand at the time and I found it hard to believe an amplifier could sound so bad.

I proceeded to connect the LS-2 to the HCA-2200 and I could not believe how bad it sounded. I had a feeling something was wrong with the match, so I took the LS-2 out of the system and I connected the Music Reference RM-5 MKII. The sound was instantly transformed and the system sounded wonderful.

This was more than just the sonic signatures of these two components not jiving together and the Parasound turned out to be a very nice and powerful sounding amp, but it was too late. The DNA-1 was a hot seller and the HCA-2200 was not because of a reviewer's negligence.

Stop! Decide on your speakers before proceeding any further.