Short answer: a tie on sound quality. Both are rated 3.9/5 (#503 and #516 of 1291 in-ear headphones) at nearly the same price ($34.99 vs $38), so choose on features and fit.
What the Roseselsa Ceramics MK2 does well: The median of 4 hobbyist measurements gives it a solid Harman preference score of 72 with a 2.07 dB spread, and its mids sit within about 0.9 dB of target, so vocals and instruments sound natural. It supports LDAC Bluetooth, which the Sony WI-C100 lacks. Watch for: A 7.7 dB peak near 7.9 kHz can make cymbals and sibilance sound sharp.
The Sony WI-C100 is the longer-running pick. The median of 3 hobbyist measurements gives it a solid Harman preference score of 72 with a 1.94 dB spread. It is rated for 25 hours of battery against 12 for the Roseselsa Ceramics MK2. The tradeoff: Presence sits about 3.4 dB low with an 8.1 dB dip near 10.3 kHz, so vocals and instruments lose some bite.
Buy the Roseselsa Ceramics MK2 or the Sony WI-C100 on features: they are rated the same for sound quality at close to the same price.
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The median of 4 hobbyist measurements gives it a solid Harman preference score of 72 with a 2.07 dB spread, and its mids sit within about 0.9 dB of target, so vocals and instruments sound natural.
Amazon $34.99 eBay
The median of 3 hobbyist measurements gives it a solid Harman preference score of 72 with a 1.94 dB spread.
Amazon $38.00 Lowest Sony $39.99 eBayPrices on this page were last checked October 16, 2026 at 5:46 PM UTC. Product prices and availability are accurate as of that date/time and are subject to change; the price and availability shown on Amazon at the time of purchase will apply to the purchase of this product.
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Specifications Side By Side
| Roseselsa Ceramics MK2 | Sony WI-C100 | |
|---|---|---|
| Price | $34.99 | $38.00 |
| Ranked | #503 of 1291 in In-Ear Headphones | #516 of 1291 in In-Ear Headphones |
| Form Factor | In-ear | In-ear |
| Back | Closed | Closed |
| Harman Preference Score | 72 (median of 4 squig.link measurements, calibrated to AutoEQ) | 72 (median of 3 squig.link measurements, calibrated to AutoEQ) |
| Deviation From Target | 2.07 dB standard deviation | 1.94 dB standard deviation |
| Tonal Tilt | -0.48 (negative is warmer, positive brighter) | -0.49 (negative is warmer, positive brighter) |
| Sub-bass Extension | Within 6 dB of target down to 20 Hz (-0.4 dB at 30 Hz) | Within 6 dB of target down to 20 Hz (-2.2 dB at 30 Hz) |
| Connection | True wireless | Wireless |
| Driver Type | Dynamic | Dynamic |
| Drivers | 1 x 10mm dynamic | 1 x 9mm dynamic |
| Frequency Response | 20Hz - 20kHz (Manufacturer specified) | 20Hz - 20kHz (Manufacturer specified) |
| Weight | 0 lbs (4.3 g) per earbud | 0 lbs (20 g) |
| Active Noise Cancelling | Yes | No |
| Battery Life | 12 hours (45 with case, Manufacturer specified) | 25 hours (Manufacturer specified) |
| Bluetooth Version | 6.0 | 5.0 |
| Bluetooth Codecs | SBC, AAC, LDAC | SBC, AAC |
| Built-in Microphone | Yes | Yes |
| IP Rating | IPX4 | IPX4 |
Frequency Response Compared
Both headphones’ measurements overlaid on the Harman target. Above the target sounds louder in that range, below it quieter. Each curve is the median of several independent measurements, shifted so its 500 Hz to 2 kHz average sits at 0 dB, so only the tuning is compared.
Measurement data: the Roseselsa Ceramics MK2 from csi-zone, digaoreviews, regancipher and soundignity; the Sony WI-C100 from aquaphobic, kazi and soundignity, all via squig.link.
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