Guides
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.
What’s the real difference between DSD and PCM? Is DSD256 worth changing your source for? The trade-offs we measured with KEYSION 02
Written for dongle users who keep going back and forth on DSD. DSD and PCM are two different digital audio encodings: DSD approximates the waveform with a high-sample-rate 1bit stream, PCM uses multi-bit sampling. Most people can’t tell them apart, and native DSD256 releases are scarce. Using KEYSION 02 and 02 Pro measurements, we show when it’s actually worth the effort.
Do Higher SNR, Dynamic Range, and Distortion Numbers Really Sound Better? What KEYSION 02 Pro’s Measured Data Means Versus What You Actually Hear
For people who want to read a spec sheet without getting led astray by numbers. SNR, dynamic range, and distortion describe how noisy a device is and how much detail it keeps, but they don’t describe whether it sounds good. Measured data from the KEYSION 02 Pro, 02, and 01 shows which specs matter and which you can skim.
Where can I find lossless music? Hi-Res download sources and format conversion (getting source files for KEYSION 02 Pro)
Once you own a Hi-Res headphone or DAC, the real gap is lossless source files. This piece covers legal buying sources like Qobuz, Bandcamp and the Japanese HiRes stores, explains CD ripping and format conversion, and shows how to spot upsampled “fake Hi-Res”.
Dongle DAC won’t connect to your phone or gives no sound? An OTG compatibility troubleshooting checklist (KEYSION S1/S2 used as the example)
A USB-C dongle DAC plugged into the phone does nothing. Most of the time the device isn’t broken; it comes down to a system permission, power, or contact issue. This guide walks an ordered OTG checklist and keeps Android and iPhone apart.
Why Does a Headphone Cable Pick Up Noise? How Much Shielding and Crosstalk Actually Matter (Tested with KEYSION 24G)
For short home-run cables, most noise comes from the connector and the source, not the wire. This post covers shielding and crosstalk, when they really matter, and a noise-hunt checklist.
Does a Bad Eartip Fit Kill the Bass? How Seal and Fit Shape IEM Sound (Tested with KEYSION 30A Foam Tips)
Most 'missing bass' problems start with the eartip and the fit, not the IEM. This post explains why seal decides the low end, silicone vs. foam tips, and how to check your fit.
Class A, AB and D Headphone Amps: How Does the Output Stage Shape the Sound? (Measured on the KEYSION 02 Pro and 02)
This article explains the real differences between Class A, AB and D output stages: the class mainly affects efficiency, heat and idle power, while audible differences are often masked by signal-to-noise ratio, gain and headphone matching. Using measured specs of the KEYSION 02 Pro and 02, it argues the class is not the deciding factor for sound quality.