Beginning around 2000, some music no longer sounded as clear or rich as it once did. The problem wasn’t the artists; rather, it was the MP3, a technology designed to maximize portability. MP3s employ audio-data compression to reduce file bandwidth, which lets you carry thousands of songs in your phone but limits the music’s dynamic range. That’s why some audiophiles began returning to LPs, which better replicate a song’s sonic footprint. Last year, vinyl sales increased by 33 percent. But you can’t carry a record player around.