The JBL PartyBox 520 features high output levels and sound quality praised by reviewers, with the bass being a particular highlight.

Powerful Sound: Delivers 400 W RMS of powerful JBL Pro Sound with deep bass, enhanced by new AI Sound Boost technology.
Dynamic Light Show: Features a built-in futuristic light show with glowing patterns and strobe effects that sync to the beat of the music.
Portability: Designed with a telescopic handle and wide wheels for easy transport, despite its substantial weight of around 25.5 kg.
Durability: It has an IPX4 splash-proof rating, meaning it can withstand spills and light rain, making it suitable for poolside or backyard parties.
Connectivity:
- Bluetooth 5.4 for wireless streaming.
- Multiple inputs including two XLR ports for microphones, guitars, or DJ consoles, as well as Aux-In and USB ports.
- Auracast™ support allows for seamless multi-speaker pairing for an even bigger sound experience.
Battery Life: Offers up to 15 hours of playtime; the battery is user-replaceable (extra batteries sold separately).
JBL PartyBox App: Provides full control over music, EQ settings, and lighting effecs

Pros: Reviewers on platforms like Trusted Reviews and SoundGuys highlight the excellent sound quality, top-of-the-line lighting effects, and versatile connectivity options. Experts at LBTechreviews note its ability to retain clarity and control even at high volumes.

Cons: Some sources mention that how the speaker sounds can be sensitive to listening angles because of its front-facing design, and that the Bluetooth latency is a bit elevated, which might cause slight lip-sync issues with video content. It is also noted that the mid-range sound is not as crisp as some other speakers, favoring a V-shaped sound curve best for party music.