Question Why Beyerdynamic DT 990 PRO is so quiet?

[kaizerSoze05]

Today i got my DT PRO 990 (250 Ohm) and dac/amp Fiio BTR15. I tested out them but headphone seems really quite. I couldnt understand the loud difference even if I connect DT 990 to laptop directly. I also tested out alone my BTR15 with my old Beats in-ear and Beats became totally something else. I checked the gain level, it was always on HIGH mode. I dont understand the headphone cant be that quiet. What am i missing?

 

[Ralston18]

TS, TRS, TRRS.

Tip, Ring, Sleeve.

Check the existing connections/pinouts.

Could be some mismatch and/or standard differences.

FYI:

https://www.cablechick.com.au/blog/understanding-trrs-and-audio-jacks/

Check all pins and ports.

 

[kaizerSoze05]

Pin has a special type at the end for 6.3 jack adapter connection but my actual connection with default 3.5 single-ended like below:

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[BFG-9000]

Beyerdynamic has a page that explains this and even has a handy calculator.

The short of it is you are using a 250-Ω load on an amp designed for 32-Ω. So since that BTR15 is rated 340mW @32Ω, it can only deliver 44 milliwatts into 250-Ω. And that's pretty quiet.