Preamp for mc275le. Need advice, please

I upgraded my Rotel 1582MkII power amp and got an MC275. Paired with a Rotel RC-1550 it swept me off my feet, literally. The tubes sound amazing! Then I wanted the ultimate warmth and decided to get a C2500. Well, it's easy these days, so I got it yesterday. Paired MC275 with C2500 and it's a huge miss. The sound of Rotel was much better. The price difference doesn't really mean that the sound will be $5K better. I guess, the sound is warm, but it's far from clear and detailed. Probably, audiophiles here will scorn me, but I'm going to give that C2500 another week or two and then I'll take it back to the store and get another Rotel. I was too quick to put it on eBay and it was sold overnight literally. I wish I had bought that C2500 from my local Best Buy so I could have returned it for a full refund without paying a restocking fee. I wish I hadn't sold my Rotel preamp. I'm at a difficult junction now, but my Bose car stereo now sounds better than that C2500 as ridiculous as this statement sounds, but it's true.