This is a report for professionals with a suite of test of headphone amplifier.
You can see a simple report for "dummies" with explanations of the main characteristics for Dared EF-99 Mid Gain

A suite of tests for a headphone amplifier can be applied to just a universal output without a formal presence of an amplifier, if in this mode you can connect headphones to this output. Based on the results of the tests, you can understand the real picture, is the output powerful enough or not, with the initial data on the circuitry as a "black box".

Line-out, differences from the output for headphones and speakers

Advantages and disadvantages of balanced amplifiers

Test report - general data Dared EF-99 (as headphone amplifier)

Frequency response, Impedance and Frequency response with standard headphones

Voltage levels from the load at the output of the amplifier

Average value of impedance band in 40 Hz - 15 kHz	6.4	ohm
Voltage: Linear Mode / Maximum or before clipping level	9.8/11.8	dBV
	3.1/3.9	V_RMS
Current: Linear Mode / Maximum or before clipping level	26.5/38.5	dB(mA)
	21.1/84.5	mA

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Frequency response Dared EF-99 Mid Gain (as headphone amplifier)

Graphics setting view

Channel

Range

Channel:	Left	Right
Variation in frequency response in band from 40 Hz - 15 kHz	-0.1, +0.0	-0.0, +0.0	dB

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On the frequency response comparison page, there is an export option and additional tools for adjusting the frequency response

Impedance Dared EF-99 Mid Gain (as headphone amplifier)

Graphics setting view

Channel

Channel:	Left	Right
Impedance average in band from 40 Hz - 15 kHz	6.8	6.0	ohm
The minimum value in band from 40 Hz - 15 kHz	6.7	5.8	ohm
The maximum value in band from 40 Hz - 15 kHz	7.3	6.7	ohm

Comparison of basic characteristics AMPs

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Crosstalk Dared EF-99 Mid Gain (as headphone amplifier)

Graphics setting view

Channel

Range

Load

Channel:	Left	Right
Crosstalk @ 1 kHz @ 15.8 ohm	-49.6	-48.7	dB
Crosstalk @ 1 kHz @ 24.5 ohm	-52.5	-51.7	dB
Crosstalk @ 1 kHz @ 30.5 ohm	-54.2	-53.4	dB
Crosstalk @ 1 kHz @ 62.4 ohm	-59.2	-58.7	dB
Crosstalk @ 1 kHz @ 100.0 ohm	-62.2	-61.7	dB
Crosstalk @ 1 kHz @ 198.9 ohm	-64.9	-65.0	dB
Crosstalk @ 1 kHz @ 300.0 ohm	-65.7	-66.0	dB
Crosstalk @ 1 kHz @ 763.0 ohm	-66.4	-66.6	dB
Crosstalk @ 1 kHz @ Not loaded	-66.6	-66.7	dB

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Crosstalk Phase Dared EF-99 Mid Gain (as headphone amplifier)

Graphics setting view

Channel

Load

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Frequency response Dared EF-99 Mid Gain with resistive load

Graphics setting view

Channel

Range

Frequency response of amplifier with resistive load @ 40 Hz - 15 kHz

Channel:	Left	Right
TEST 16 ? + Dared EF-99 Mid Gain	0.3	0.4	dB
TEST 32 ? + Dared EF-99 Mid Gain	0.2	0.3	dB
TEST 64 ? + Dared EF-99 Mid Gain	0.1	0.1	dB
TEST 126 ? + Dared EF-99 Mid Gain	0.1	0.1	dB
TEST 256 ? + Dared EF-99 Mid Gain	0.0	0.0	dB
TEST 512 ? + Dared EF-99 Mid Gain	0.0	0.0	dB

Brief information

Clicking on the graph will take you to the comparison page of different models with advanced graph display settings.

On the frequency response comparison page, there is an export option and additional tools for adjusting the frequency response

Frequency response Dared EF-99 Mid Gain loaded dynamic headphone type

Graphics setting view

Channel

Range

Frequency response of amplifier loaded dynamic headphone type @ 40 Hz - 15 kHz

Channel:	Left	Right
TEST 10000 ? + Dared EF-99 Mid Gain	0.0	0.0	dB
Grado GH4 Limited Edition + Dared EF-99 Mid Gain	1.1	1.0	dB

Brief information

Clicking on the graph will take you to the comparison page of different models with advanced graph display settings.

On the frequency response comparison page, there is an export option and additional tools for adjusting the frequency response

Frequency response Dared EF-99 Mid Gain loaded type balance armature headphone type

Graphics setting view

Channel

Range

Frequency response of amplifier loaded type balance armature headphone type @ 40 Hz - 15 kHz

Channel:	Left	Right
TEST 10000 ? + Dared EF-99 Mid Gain	0.0	0.0	dB
Campfire Audio Andromeda + Dared EF-99 Mid Gain	6.9	6.2	dB
Fearless Audio S8F Freedom + Dared EF-99 Mid Gain	5.8	5.1	dB

Brief information

Clicking on the graph will take you to the comparison page of different models with advanced graph display settings.

On the frequency response comparison page, there is an export option and additional tools for adjusting the frequency response

THD vs load vs output voltage Dared EF-99 Mid Gain

Graphics setting view

Channel

Load

Harmonic, number

Graphics setting view

Channel

Load

Harmonic, number

Graphics setting view

Channel

Load

Brief information

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Maximum voltage output level vs load Dared EF-99 Mid Gain

Graphics setting view

Type of chart

RAW coordinates

Power characteristics of the	Voltage		Current
	dBV	V_RMS	dB(mA)	mA
Equivalent class A	9.8	3.1	26.5	21.1
Equivalent class AB	11.8	3.9	32.3	41.0
Equivalent class B	11.8	3.9	38.5	84.5
Maximum mode	11.8	3.9	38.5	84.5

Volume Control Type	Analog
Optimal range of volume control	36.0	dB

Comparison Dared EF-99 Mid Gain and another amplifiers by loudness (Volume Level)

Main characteristics of the Dared EF-99 Mid Gain

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Maximum voltage output level vs load Dared EF-99 Mid Gain

Graphics setting view

Type of chart

RAW coordinates

Maximum Amplifier Voltage Level

Load	Pure or equal class A		Optimal or equal class AB		Hard or equal class B		Max, before clipping
	dBV	V_RMS	dBV	V_RMS	dBV	V_RMS	dBV	V_RMS
15.8 ohm	-12.1	0.2	-3.1	0.2	1.8	0.2	1.8	0.2
24.5 ohm	-6.2	0.5	-3.2	0.5	3.8	0.5	3.8	0.5
30.5 ohm	-4.0	0.6	1.9	0.6	5.9	0.6	5.9	0.6
62.4 ohm	3.0	1.4	9.0	1.4	9.0	1.4	9.0	1.4
100 ohm	7.3	2.3	10.2	2.3	10.2	2.3	10.2	2.3
198.9 ohm	9.5	3.0	11.5	3.0	11.5	3.0	11.5	3.0
300 ohm	9.6	3.0	11.6	3.0	11.6	3.0	11.6	3.0
763 ohm	9.7	3.1	11.7	3.1	11.7	3.1	11.7	3.1
Not loaded	9.8	3.1	11.8	3.1	11.8	3.1	11.8	3.1

Maximum level of amplifier current

Load	Pure or equal class A		Optimal or equal class AB		Hard or equal class B		Max, before clipping
	dB(mA)	mA	dB(mA)	mA	dB(mA)	mA	dB(mA)	mA
15.8 ohm	23.9	15.6	32.9	44.1	37.9	78.3	37.9	78.3
24.5 ohm	26.0	20.0	29.0	28.2	36.0	63.2	36.0	63.2
30.5 ohm	26.3	20.6	32.3	41.0	36.2	64.9	36.2	64.9
62.4 ohm	27.1	22.6	33.1	45.0	33.1	45.0	33.1	45.0
100 ohm	27.3	23.1	30.2	32.5	30.2	32.5	30.2	32.5
198.9 ohm	23.6	15.1	25.5	18.9	25.5	18.9	25.5	18.9
300 ohm	20.1	10.1	22.0	12.6	22.0	12.6	22.0	12.6
763 ohm	12.1	4.0	14.0	5.0	14.0	5.0	14.0	5.0

Power

Load	Pure or equal class A		Optimal or equal class AB		Hard or equal class B		Max, before clipping
	dBm	mW	dBm	mW	dBm	mW	dBm	mW
15.8 ohm	5.9	3.9	14.9	30.7	19.9	96.9	19.9	96.9
24.5 ohm	9.9	9.8	12.9	19.5	19.9	97.7	19.9	97.7
30.5 ohm	11.1	12.9	17.1	51.3	21.1	128.4	21.1	128.4
62.4 ohm	15.0	31.9	21.0	126.2	21.0	126.2	21.0	126.2
100 ohm	17.3	53.5	20.2	105.9	20.2	105.9	20.2	105.9
198.9 ohm	16.5	45.1	18.5	70.7	18.5	70.7	18.5	70.7
300 ohm	14.8	30.5	16.8	47.8	16.8	47.8	16.8	47.8
763 ohm	10.9	12.3	12.9	19.3	12.9	19.3	12.9	19.3

Brief information

Clicking on the graph will take you to the comparison page of different models with advanced graph display settings.

Spectrum of Total Harmonic Distortion vs Level Dared EF-99 Mid Gain (as headphone amplifier)

Graphics setting view

Channel

Level

Range

Graphics setting view

Channel

Level

Range

Graphics setting view

Channel

Shift

dBm

Range

Graphics setting view

Channel

Shift

dBV

Range

Brief information

Clicking on the graph will take you to the comparison page of different models with advanced graph display settings.

Spectrum of Multitone Distortion vs Level vs Load Dared EF-99 Mid Gain (as headphone amplifier)

Graphics setting view

Channel

Level

Range

Graphics setting view

Channel

Level

Range

Graphics setting view

Channel

Shift

dBm

Range

Graphics setting view

Channel

Shift

dBV

Range

Brief information

Clicking on the graph will take you to the comparison page of different models with advanced graph display settings.

Spectrum of IMD SMPTE vs Level Dared EF-99 Mid Gain (as headphone amplifier)

Graphics setting view

Channel

Level

Range

Range

Graphics setting view

Channel

Level

Range

Range

Graphics setting view

Channel

Shift

Range

dBm

Range

Graphics setting view

Channel

Shift

Range

dBV

Range

Brief information

Clicking on the graph will take you to the comparison page of different models with advanced graph display settings.

Spectrum of IMD CCIF vs Level Dared EF-99 Mid Gain (as headphone amplifier)

Graphics setting view

Channel

Level

Range

Graphics setting view

Channel

Level

Range

Graphics setting view

Channel

Shift

dBm

Range

Graphics setting view

Channel

Shift

dBV

Range

Brief information

Clicking on the graph will take you to the comparison page of different models with advanced graph display settings.

More detailed

Measurements of Dared EF-99 Mid Gain were carried out by Roman Kuznetsov on the hardware-software complex RAA.

The Dared EF-99 Mid Gain test was conducted as a black box test, without regard to cost and prestige. This is the basic principle for making measurements, measurement reports and developing tests in RAA.

I believe that it is important to do not make an absolute assessment of the device, but an aggregate assessment when working together with a headphones and taking into account external factors. This allows you to effectively reveal the potential of the entire set of devices or to make a more optimal choice of components.

Kuznetsov Roman
Founder of RAA

Known by the nickname romanrex
Аuthor of articles iXBT.com

Information for Authors. You can freely use the graphics in your articles with a link to us.

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