I'm going to join with Plato here. My experience has been that when all other factors are equal, the 45 rpm release will sound better in almost every sonic category you can name, assuming your system is capable of resolving these differences. If you're not hearing a difference, you've probably reached the limit of what your current system will resolve (as Plato suggests). FWIW, I've previously offered some comments about my comparison of the
Classic Records classical reissues at 33 vs 45 rpm. More recently, I've listened to a lot of the Analogue Productions 45 rpm jazz reissues comparing some of those to AP's 33 rpm reissues of the same recordings. The overall sonic differences between 33 and 45 rpm releases continue to hold true, with the 45 rpm versions being clearly better in multiple ways.
Please understand that I have hundreds of 33 rpm LPs that are sonically excellent and often outstanding. I'm simply reporting that my experience consistenly has been that an excellent sounding recording at 33 rpm will sound even better when mastered at 45 rpm. Two quick examples from the Classic Records reissues: the Rozsa/Hendl/Heifitz RCA LSC-2767 and the Stravinsky/Firebird Mercury SR90226. Both are excellent in their 33 rpm versions, but both are clearly better in their 45 rpm incarnations.
While I obviously disagree with Jaybo's assessment of the sonic differences between 33 and 45 releases, I do agree with his caveate about the music being interrupted by the short playing sides of 45 rpm LPs and the impact this has on the "magic of continuity."
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