Q: Will I have to replace my CD player and compact-disc library? A: Not anytime soon. Both new systems will play conventional CDs, and most new discs will work (though not optimally) in your old CD player. Record companies are starting to release popular music titles in both formats, but they have no plans to stop pressing conventional CDs. Q:So what’s the bottom line–should I buy Super Audio now? A: Only if you’re an audiophile. It’s pricey: the Sony Super Audio CD player (SCD-1) costs $5,000, and Super Audio discs are each about $25. But you will hear the difference. If you do buy now, your investment is safe: experts predict that both DVD Audio and SACD will likely survive because both reside on CD-size discs. Unlike the VHS and Betamax machines from the previous standards war, future home audio players should be able to read both of these new formats.