The Mac G-6 is the recommended platform for music/video now. It's alot more expensive (double at least) but it can support 96.1/32 audio recording with the proper input card and software, and "process it" in nearly "real-time".
It is plainly difficult to digitize analogue audio well . But as I do with old movies, what is possible in the digital world, is just impossible otherwise. My old poor quality "acid rock" LP's sound so much better than new after "working" on them, there is no comparison, and the master tapes are all either gone or sitting in a basement closet deteriorating in the great-nieces'/nephew's house. 99.9% of the artists didn't make it thru the '80's alive, and the "record companies" have all disappeared. I've seen four make it to CD's and they sound like someone took really beat-up LP's and just transferred them to CD with a $25 USB pre-amp and didn't even clean the LP's. I returned them. My LP's sounded better than the "commercial" CD's. Working from a real master tape, there is no reason a CD couldn't "eat" LP reproduction alive, except for lazy, lousy recording "engineers" of today, who believe "louder is better". My mid-30's 78's "half-speed mastered" to audio tape, and very lightly "processed" sound better than most 50's era CD's (Dean Martin, Tony Bennett, Al Martino, Gogi Grant, Frank Sinatra, etc.) on the market. Thankfully, I have 99% of these on original vinyl's, many in "mint+" condition from my estate sales crawling. I have "old Blue Eyes" on BlueBird and Columbia 78's, just post WWII. The REAL recording engineers of that era had the "78 format" just about figured out by then. Some of them are pretty hard to tell they're 78's. They're on "quiet" acetate records, and somebody KNEW what they were doing in the production process.