Fiio FD 15 VS Letshuoer S12 Ultra

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LETSHUOER S12 Ultra wraps up the S12 line with a 14.8 mm planar driver and a familiar metal shell in gunmetal or mocha. The housing is vented, comfy for long sessions, and solidly built with a flat 2-pin interface that grips tips well. The stock package is practical: a soft case, a fair tip spread, a braided cable with swappable 4.4 mm termination, and even a plug-and-play USB-C DAC that performs capably for on-the-go use.

Sonically, this set aims for a mild V-shape with tasteful tweaks that elevate it over prior S12 iterations. There’s a touch more sub-bass than the S12 Pro and a smoother 10 kHz zone, reducing fatigue while keeping upper-treble reach for air. The presentation favors balance over sparkle: detailed without the brittle edge many planars flirt with, and notably non-fatiguing over longer listens. Technical chops are strong for the class—clean, clear, and “planar-fast”—though instrument separation can lag behind pricier hybrids, and the topmost “crispy” sheen is slightly restrained.

On graphs and in practice, S12 Ultra reads as a refined take on modern planars—more bass weight, tidier 4–6 kHz, and better treble behavior than its siblings. Listeners hypersensitive up top may still prefer something like the S15 for a softer treble contour, while those chasing maximal separation may lean to sets like AFUL Performer 7 (with a spicier treble). With the usual planar caveat about unit variance and fit, this edition comes through as the standout of the S12 series: a clean, engaging, and genuinely high-value recommendation under $500.