Short answer: a tie on sound quality. Both are rated 3.7/5 (#657 and #664 of 1291 in-ear headphones) at nearly the same price ($200 vs $199), so choose on features and fit.
What the Akoustyx S-6 does well: A single planar magnetic IEM with full sub-bass extension to 20 Hz and a Harman preference score of 70 across three measurements. The catch: Treble sits about 2.4 dB above target, so it can sound bright.
What the Rumaudio Blues does well: An all balanced armature IEM with six drivers per side. The tradeoff: Bass sits about 2.0 dB below target, so it sounds lean.
Buy the Akoustyx S-6 or the Rumaudio Blues on features: they are rated the same for sound quality at close to the same price.
Still deciding? The full Headphones rankings cover every ranked option.
A single planar magnetic IEM with full sub-bass extension to 20 Hz and a Harman preference score of 70 across three measurements.
Akoustyx $200.00 eBay
An all balanced armature IEM with six drivers per side.
Shenzhenaudio $199.00 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
| Akoustyx S-6 | Rumaudio Blues | |
|---|---|---|
| Price | $200.00 | $199.00 |
| Ranked | #657 of 1291 in In-Ear Headphones | #664 of 1291 in In-Ear Headphones |
| Form Factor | In-ear | In-ear |
| Back | Closed | Closed |
| Connection | Wired | Wired |
| Driver Type | Planar Magnetic | Balanced Armature |
| Drivers | 1 x planar magnetic | 6 x balanced armature |
| Impedance | 18 ohms | - |
| Sensitivity | 108 dB SPL | - |
| Harman Preference Score | 70 (median of 3 squig.link measurements, calibrated to AutoEQ) | 70 (median of 4 squig.link measurements, calibrated to AutoEQ) |
| Deviation From Target | 2.24 dB standard deviation | 2.43 dB standard deviation |
| Tonal Tilt | -0.32 (negative is warmer, positive brighter) | +0.25 (negative is warmer, positive brighter) |
| Sub-bass Extension | Within 6 dB of target down to 20 Hz (+5.2 dB at 30 Hz) | Within 6 dB of target down to 20 Hz (-4.7 dB at 30 Hz) |
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 Akoustyx S-6 from dentreviews, superreview and treblewellxtended; the Rumaudio Blues from audioamigo, bedrock, flare and soundcheck39, all via squig.link.
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