ESI U24 XL USB Audio Interface, 24-bit with Optical and Coaxial S/PDIF

Some recording setups mainly need straightforward analogue connections, others also need a way to route digital audio. The ESI U24 XL caters for both, combining two analogue input and output channels with optical and coaxial S/PDIF input and output in a compact USB interface for PC and Mac.

At 10 x 9 cm, it is small enough to fit into a compact studio setup or travel kit. Its feature set is more specialised than a basic analogue-only interface, so the useful question is whether you will make use of its digital connections.

Tips for day-to-day use

The U24 XL connects over USB and provides two analogue inputs and two analogue outputs with jack connections. Output L can also serve as a headphone output, which gives you a monitoring route without requiring a separate headphone socket. Real-time monitoring is specified for incoming audio, and the product information lists ASIO 2.0 driver support for Windows and Core Audio support for Mac OS X.

For a practical home-recording setup, you could connect an analogue source to the inputs, monitor the incoming signal, and use the outputs to feed your listening setup. The optical and coaxial S/PDIF connections are useful when your equipment has matching digital connections and you want to include them in the same USB-based setup. The stated maximum sample rate is 192 KHz, with 24-bit AD/DA conversion.

The compact silver unit measures 10 x 9 cm, but its analogue side is limited to two input and two output channels. It is worth matching that channel count to your planned sources before choosing it, the digital connections add routing options, rather than extra analogue inputs.

Where it shines

The main distinction here is the combination of analogue jack connections and both optical and coaxial digital I/O. That can suit a small studio or desk where you need to connect analogue gear as well as equipment with S/PDIF, without making the interface itself the centre of a larger rack setup. Its small footprint also makes it easier to place alongside a computer when desk space is limited.

Compared with a simpler interface focused only on analogue connections, the U24 XL offers more ways to connect digital sources and destinations. In a scenario where all your recording sources are analogue and you do not need S/PDIF, those extra connections may not influence your decision much. It might not be a great match if your setup requires more than two analogue inputs at once.

Key takeaways

The buying case rests on its connection mix, USB operation and compact size, rather than a high analogue channel count. It’s a good fit if you want a small PC or Mac interface with two analogue input and output channels, real-time monitoring and optical and coaxial S/PDIF. The 24-bit conversion and stated 192 KHz maximum sample rate add useful technical context, but the practical benefit depends on the equipment and recording workflow you intend to use.

The product information names Windows and Mac support, and specifies drivers for Windows versions including Windows 10 and Core Audio support for Mac OS X. Cubase LE is listed as supplied software. Check that the stated operating-system support and software details suit your computer before buying, particularly if you rely on a specific setup.

Buying verdict

Choose the ESI U24 XL when a small USB interface with two analogue channels and optical and coaxial S/PDIF matches the equipment you already use. It is a more considered choice than an analogue-only unit if digital audio connections matter to your setup. If you need to record several analogue sources simultaneously, its two-input layout is the key reason to look at a different type of interface.