Dedicated Desktop Mode When in the dedicated desktop mode and under USB fast charging, the M15S will transform essentially into a desktop device and work completely without the battery. That is, under this mode the battery will neither be charged nor discharged, preventing premature battery degradation. Robust Performance Everywhere The M15S not only features the desktop and portable dual power supplies as seen in other FiiO products but is also equipped with an automatic auxiliary DC power supply. The M15S is able to automatically recognize when fast charging through USB is being used, and automatically switches to use the highest-voltage power supply, leading to an increase of 26.67 percent in power supply for even more power output.
Even when not using the fast-charging adapter, the M15S can still automatically switch to a higher-voltage power supply that is enough to drive most headphones. Near-Desktop Power The M15S can be adjusted with five levels of gain. Under battery power, low, medium, high, and over-ear headphone gain levels can be selected. When under USB power, the enhanced over-ear headphone gain level is also available, enabling undistorted power output up to 1200 mW per channel, easily enough to drive a wide variety of IEMs and headphones. Six Operating Modes Including Roon Ready Firstly, there is Pure Music mode, a FiiO-exclusive mode, for immersive music.
Second is Android mode which freely uses third-party apps, including those of streaming services. Next is AirPlay mode wirelessly connect to iOS devices like iPhone or iPad, with a sound quality boost. Fourth is Roon Ready mode which is Roon Ready certified, for serious music lovers. Fifth is USB DAC mode which acts as a DAC when connected to a computer or phone, for greatly improved sound. Finally, there is the Bluetooth Receiver mode that supports SBC, AAC, aptX, aptx HD, aptx LL, LDAC, and apt Adaptive, for convenient quality wireless sound.
Overbuilt Power Supply for Ample Clean Power Anytime Fully separated digital power supply, effectively reducing crosstalk, and interference. Multi-stage analog power supply, high-precision, and low noise for early signal processing. Multi-voltage servo power supply for headphone amp, capably driving low and high-impedance loads. High-Performance ES9038PRO DAC Desktop-Grade Part The full, uncut desktop ES9038PRO DAC chip with eight independent D and A converters is employed in the M15S. Each channel uses four D and A converters in parallel to form a fully differential output, for a truly rich and highly resolving sound.


