250 Ω DT 770 from an iPad Air: the interface that can drive them needs the whole power budget
The 250 Ω DT 770 needs 2.51 V. The iD4 MkII delivers 5.46 V — 6.8 dB of headroom — and asks for 0.9 A at 5 V, exactly the iPad Air's allowance without a Power Delivery contract.
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)
Yes: 116.8 dB, 6.8 dB of headroom — and the reason to check this pairing is the power contract, not the volume.
The 250 Ω DT 770 Pro is 96 dB/mW, i.e. 102.0 dB/V, so a 110 dB peak needs 2.51 V, 25.12 mW, 10.02 mA. Audient publishes the iD4 MkII headphone output as a voltage rather than a decibel figure — «MAXIMUM LEVEL @ 600R: 5.46 V RMS, 100 mW» — and 5.46 V into 250 Ω is 116.8 dB. Together with its bigger sibling the iD14 MkII, which publishes the same 5.46 V, it is the strongest bus-powered interface in this catalogue, and it settles this headphone comfortably.
Now the other side of the cable. Audient also publishes the bus requirement: 0.9 A at 5 V, i.e. 4.5 W. Apple gives the iPad Air 11-inch M3 1.5 A over USB Power Delivery (7.5 W) and 900 mA without it. So the interface fits — but at the non-PD allowance it fits exactly, with nothing left, and anything else on the same port changes the answer. The cheaper route does not work at all: an EVO 4 at 2.48 V reaches only 108.3 dB on these headphones, 1.7 dB short of target, and its published «<50 Ω» output impedance gives a damping ratio of 5 against the 8 the rule asks.
The pearl: almost nobody publishes the bus current, and Audient does. Across this catalogue, PreSonus, SSL, Audient's own EVO line, FiiO and Hidizs state only «USB bus powered» or nothing at all, and the figures recorded for them are the USB 2.0 default allotment — 500 mA at 5 V — marked as an assumption, not a specification. That is why «will this interface run off my tablet» so often has no honest answer beyond «the manufacturer does not say». Here it does say, and the answer is a clean yes.
What we cannot check. Audient publishes no output impedance for the iD4 MkII. Against 250 Ω the 1/8 rule wants 31 Ω or less — a bar most interfaces clear — but we have no figure, so 116.8 dB is the optimistic ceiling and the tonal balance is unknown. Also worth noting that the iPad Air's 7.5 W is half the budget of an iPad Pro with the same connector and the same silicon family: the difference is in the power path, not the chip.