Desktop headphone amplifiers are larger, more powerful amplifiers that are designed to be used at a fixed location, such as a home or studio. They typically have more features and higher output power than portable amplifiers, and are often used to drive high-impedance headphones or multiple pairs of headphones simultaneously. Desktop amplifiers are often powered by an AC outlet and may have larger input and output connections, such as XLR or RCA jacks.
Portable headphone amplifiers, on the other hand, are smaller and more compact, and are designed to be carried and used on the go. They are typically powered by a battery or a USB connection, and have smaller input and output connections, such as 3.5mm jacks. Portable amplifiers are often used with portable devices, such as smartphones or MP3 players, and are convenient for traveling or on the go.
When deciding between a desktop and a portable headphone amplifier, consider the type of headphones you are using, the type of source device you are connecting to, and your intended use. A desktop amplifier may be the better choice if you need a powerful amplifier for use at a fixed location, such as a home or studio. A portable amplifier may be more suitable if you need a compact amplifier for use on the go.