Pixel 10 + Hidizs S9 Pro Plus + DT 700 Pro X: one impedance instead of three
48 Ω at a stated 100 dB SPL (1 mW / 500 Hz) works out to 113.19 dB/V and needs 0.693 V. The dongle's 2.1 V reaches 119.6 dB — 9.6 dB of headroom from a phone. The unit in beyerdynamic's own line is what makes the number readable.
Signal Chain Compatibility Matrix
Select gear and parameters for live gain, impedance and SPL calculations.
Input Equipment Setup
PASS: Optimal Signal Chain
Requires minimum +60dB of clean pre-amp gain. Most budget entry interfaces max out at +50dB to +56dB and introduce hiss at max pot. An inline preamp booster (Cloudlifter CL-1 / FetHead) is strongly recommended.
The interface preamp provides sufficient headroom.
$538
$405
-25%Tonal & acoustic characteristics: Flat, wide-range frequency response for clean music and speech. Smooth, warm acoustic character with air-suspension shock isolation.
Technical advisory: With +69dB max gain, the Gen 4 Solo can drive demanding dynamics like the Shure SM7B natively without requiring an external inline booster.
Physical Interconnect Topology
Shure SM7B
Direct Cable Connection (No Intermediate Box)
1x Shielded Balanced XLR Cable (3-Pin XLR Male to XLR Female)
Focusrite Scarlett Solo (Gen 4)
Host: Apple MacBook Pro (M1/M2/M3/M4)
The DT 700 Pro X is beyerdynamic's answer to the impedance-version problem: one 48 Ω model instead of three. On a phone dongle that turns out to be the right answer.
The sensitivity line reads 100 dB SPL (1 mW / 500 Hz), so at 48 Ω the conversion gives 113.19 dB/V and a 110 dB peak needs 0.693 V, 14.43 mA, 10.00 mW. The Hidizs S9 Pro Plus Martha reaches 2.1 V on its 3.5 mm output, which puts the chain at 119.6 dB SPL — 9.6 dB of headroom, comfortable, from a device that hangs off a phone by a short cable.
The pearl: that 2.1 V is derived, not printed. Hidizs publishes 138 mW + 138 mW into 32 Ω for the single-ended port; √(0.138 × 32) = 2.10 V. Derived-from-published is not the same as published, and it carries an assumption — that the amplifier holds the same voltage into 48 Ω as into 32 Ω. Here that assumption is cheap, because the requirement of 0.693 V sits three times below the ceiling; the same assumption would be worth arguing about if we were computing a 300 Ω headphone at the edge of the range. Always check how far you are from the edge before deciding how much a derived number matters.
Why the unit on the beyerdynamic sheet matters beyond this page. The DT 700 and DT 900 PRO X sheets are the only place in beyerdynamic's documentation where the sensitivity scale is spelled out. The classic DT 770 sheets print "Nominal SPL 96 dB" with no unit at all — and it is the PRO X line that tells you those are per milliwatt too. One product's spec sheet is the key to another's.
What we cannot check. Hidizs does not publish an output impedance. The 1/8 rule wants below 6 Ω for a 48 Ω headphone, and there is nothing to compare against, so 119.6 dB is computed without divider loss and is the optimistic end. On power: the Pixel 10's USB-C port supplies 4.5 W; our record for the dongle carries 2.5 W, but Hidizs publishes no consumption figure, so that is the USB 2.0 bus default recorded as a ceiling rather than a measurement. The 4.4 mm balanced port would give more than 2.1 V; no figure for it is published in the source we cite, so we do not compute it.