At transformers we haven´t a purely ohmic resistance. This a complex resistance. These resistance differs differs depending on the frequency- > these resisteance is called impedance.
DC-resistance ist not important for a input transformer. Please measure the imedance with a LCR-Bridge or a NTI Minirator Pro. Then you will see.
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Transformers transform impedance! There is always current flowing in a transformer when it carries a signal. Transformers can be used to transform voltage or to transform current (aka current transformer) - two sides of the same coin.
dU/dt is for capacitors, dI/dt is inductors, as the equation is L dI = V dt.
And lastly transformers are not the same as inductors, they have mutual inductance as well as self-inductance, so its a bit more complicated in real life, though to a first approximation you just think of the transformer as transforming its secondary’s load impedance by a factor to yield the impedance seen at the primary, this ratio being the square of the turns ratio.
The ideal transformer equation is Vp Ip = - Vs Is. (the negative sign because the currents are taken to flow in opposite directions so they cancel - other sign conventions are used, especially for transformers with many windings. Also Vp/Vs = np/ns is the turns-ratio equation.
If you think.
The primary task of an input transformer is to increase the level with almost no noise. It’s not about current or power or impedance but about voltage. Increasing the impedance is also not the main consideration for an input transformer. This is rather disadvantageous because it increases the noise in the subsequent amplifier and requires additional circuit measures to keep the noise low. Increasing the impedance, which does not occur linearly, is rather disadvantageous and is not the primary task of an input transformer.
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Impedance conversion is one of the primary uses of a transformer - think valve amplifier output transformers increasing a speakers impedance so the valves can drive them. And, transformers aren’t always used to increase voltages either they are often intended to decrease voltages - think valve amplifier output transformers decreasing their voltage so speakers can be driven with a suitably lower voltage. Plus, transformers also transform current - think valve amplifier’s output current being increased so they can drive 8R/4R etc speakers. It all depends on how you look at it: valves need to see high impedances and use high voltages, loudspeakers need low voltages but relatively high currents.
Voltage, current and impedance transformation are all intertwined in transformer action. With high impedance (>10k) line level audio inputs/outputs the current involved is very low and so we consider them to be ‘voltage only’ inputs but obviously a current must flow to complete the circuit. If a transformer could operate with just voltage and no current, then it’s impedance would be infinite - something not quite achievable in this world yet 
Lets look…Best regards!
Power is voltage x current. The movement of a microphone’s capsule creates a voltage which in turn creates a current through whatever impedance it is connected to - the power is minuscule but it is still there. Even less power is created when a radio antenna receives a signal yet radio frequency engineers often characterise the resultant signal in terms of watts.
A transformer by definition transforms current, voltage and impedance this is because it maintains the input power. Some power is lost to winding resistance (insertion loss) and this is relevant which is why the DCR of the windings is always mentioned in a transformer’s specification sheets - this includes moving coil, microphone and line level transformers.
Then continue measuring your input transformers with the multimeter…
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Just want to confirm.
I did DCR measurement with my LCR and also my Sanwa PC5000. No negative effect so far, both from listening test (no low frequency missing) and also from the measurement with QA402. Bandwidth up to like 60kHz (-3dB) and around -0.2dB at 20Hz. Not saying I will keep doing this, but just want to share the result.
I guess the current is not enough to magnetize the core.
Thanks.
The DC voltage for the resistance test with the Sanwa multimeter is between approximately 1.3 and 3 volts.
If you think. Even if many people do it that way, it’s not right. Take a look at the documents from Studer.
Have you measured the knock microphony of the input transformer and the distortion of the transformer before and after?
By the way, input transformers work voltage-adjusted like everything in the audio world.
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Pleas look at page 3 at the beyerdynamic catalog for audio input transformer. You can go to the original pdf: audio.kubarth.com Übertrager
Best regards!