Guides
FLAC, ALAC, WAV, AIFF: What Actually Differs? How the Four Lossless Formats Work, and How to Pick (Tested on KEYSION 02)
For anyone sorting a local library and stuck on which lossless format to keep. FLAC, ALAC, WAV and AIFF decode to the same PCM stream; the real gaps are file size, tagging and device support. Here's a measured comparison, plus picks by use case.
What Is MQA? The Fold-and-Unfold Trick, the Controversy, and Whether It's Worth Enabling (Tested on KEYSION 02 Pro)
For dongle-DAC users who keep running into the MQA badge on streaming platforms and aren't sure whether to switch it on. MQA isn't a new format. It's a folding codec plus authentication layer wrapped around FLAC. This article covers how it works, why it's argued about, and how MQA, FLAC, and DSD actually differ on the 02 Pro, so you can decide whether it's worth paying for.
What Are Asynchronous USB and Jitter? Does Clock Jitter Really Affect Sound Quality (KEYSION 02 Pro Test)
Jitter is a real timing error, but modern DACs have mostly pushed it below the audible threshold. This article explains the differences between Synchronous, Adaptive, and Asynchronous USB, the order of magnitude of jitter thresholds, and when a clock is actually worth paying for.
Do Eartip Materials Change the Sound? Silicone, Foam, and Hybrid Tips Compared (KEYSION 30A Test)
Eartip material mainly changes bass sealing and treble quantity, while the midrange stays roughly in place. Using public isolation and frequency response data, this article breaks down silicone, foam, and hybrid tips, and gives a check order: seal first, material second.
What Is Soundstage and Imaging? How Headphones Create a Sense of Space
Soundstage is the width, depth and height of the sound field. Imaging is how precisely instruments and vocals are positioned. They're not the same thing — some headphones have a wide stage but blurry imaging, others have sharp imaging but a small space. Driver type, enclosure design, tuning, and even your DAC/amp all play a role. A low-distortion source like the KEYSION 02 helps imaging feel more solid.
Open-Back vs Closed-Back Headphones: Which Design Fits Your Listening Style
The real difference between open-back and closed-back headphones isn't about which sounds better — it's about where you listen and what you prefer. Open-backed models leak sound but have a wider soundstage, best for private listening. Closed-back designs isolate well and deliver more bass, ideal for commuting and offices. Paired with a DAC/amp like the KEYSION 02 Pro, both types can reach their full potential.
How to Calculate Headphone Amp Power: How Many Milliwatts Does Your Headphone Need (KEYSION 02 Pro and 02 Measured)
Driving power is not a mystery — sensitivity, impedance, and your target SPL decide how many milliwatts you need. This post gives the formula and a quick-reference table for common headphones, then checks both against measured output from the KEYSION 02 Pro (551mW@32Ω) and the 02 (361mW@32Ω).
Do DAC Digital Filter Settings Actually Change the Sound? Linear Phase vs Minimum Phase (KEYSION 02 Pro Tested)
What do the DAC filter options on a dongle DAC (linear phase/minimum phase, sharp/slow roll-off) actually change? This guide explains the differences using measured data from the KEYSION 02 Pro and tells you when switching is worth it.
Dongle DAC Sounds Weak or Keeps Cutting Out? Does the OTG Cable Matter and When to Upgrade (Tested on 01)
A dongle DAC that sounds weak or keeps cutting out is often about the OTG cable, not the headphones or the DAC. This compares a few cable types on the KEYSION 01 and explains power, data and shielding, plus when swapping actually helps.
Bluetooth Headphones Won’t Pair or Keep Dropping? A Step-by-Step Check and What Usually Causes It (Tested on X1)
Bluetooth headphones that won’t pair or keep dropping are usually not broken: stale pairing records, 2.4GHz interference and battery-saver sleep logic are the real suspects. Here’s a prioritised checklist.
Does EQ tuning on your phone actually work? How to shape your sound without making it muddy (tested on KEYSION 01)
EQ is neither magic nor a cure-all. This post spells out the difference between parametric and graphic EQ, whether digital EQ harms sound quality, and gives a KEYSION 01 dongle-tested method to tune your sound without turning it to mud.
Where does Bluetooth audio quality get lost? How much do SBC, AAC, aptX, and LDAC really differ (KEYSION S2 measured)
Bluetooth audio loss is not a mystery; most of it sits in the codec stage, not the driver. This piece covers real numbers on SBC, AAC, the aptX family, and LDAC: bitrate, sample rate, and measurable gaps, so you can decide whether chasing a higher-bitrate wireless path is worth it for your ears.