Nakamichi tape was re-branded TDK, supposedly "center cut". It is true that metal tape will perform slightly better at the frequency extremes, but I usually preferred the chrome tapes, which sounded more uniform and "musical" to me, and less expensive. The slight loss you heard is a limitation of cassette tape. It could never quite match a high-end vinyl rig. I wouldn't worry about it. The only way to come really close to vinyl is with a very fine, well adjusted, reel-to-reel; but the fact is, no copy can be as good as the origianl medium. BTW, even a "mint" Dragon almost certainly needs some attention at this point; it is pretty old, and they are very complex. I sent mine to Willy Herman, who did fine work at a very reasonable price.