Mediocre for neutral listening. The SE425 improve slightly on the sound quality of the SE315 with better a Mid and Treble range. However, they still have a big emphasis on low-mid that extends to the high-mid which makes their sound a bit boomy and muddy while pushing instruments and vocals to the forefront of any track. Unfortunately, those instruments and vocals do not sound as clear and detailed as some other in-ear headphones due to their somewhat inconsistent high tones. That and their closed-back, in-ear fit means they have a poor Soundstage that won't be ideal for more neutral listeners.