K5 vs Star One: which needs more amplifier?

The EPZ K5 is 28Ω at 114.0 dB (no reference unit printed); the EPZ Star One is 64Ω at 100.1 dB/mW. This page covers what they ask of an amplifier, not how they sound.

The Star One needs 13.9 dB more than the K5 to reach the same loudness — 0.98 mW against 0.04 mW.

Side by side

The numbers that decide it

Specification	K5	Star One
Impedance	28 Ω	64 Ω
Sensitivity	114.0 dB	100.1 dB/mW
Sensitivity (voltage)	129.5 dB/V	112.0 dB/V
Power for 100 dB	0.04 mW	0.98 mW
Voltage for 100 dB	33 mV	0.25 V
Current for 100 dB	1.2 mA	3.9 mA
Highest source impedance that leaves them alone (one-eighth rule)	3.50 Ω	8.00 Ω
Sources that reach 100 dB out of 280	280	280

One caution before reading the rows. EPZ K5 printed a decibel figure with no reference unit, so this page reads it as per milliwatt. If it is really per volt, that model needs far more than the table says. Why the two readings differ by so much.

What separates them

Where the two part company

Every source in the database that drives one of them drives the other. On power, the choice between these two changes nothing about what amplifier you need.

1 source is low enough in output impedance for the Star One under the one-eighth rule but not for the K5 (Shanling H5).

21 sources stay below the audible-hiss threshold with the Star One but cross it with the K5 (FiiO BTR11, Fosi Audio SK02, FiiO K11 R2R, 18 more).

280 of the 280 sources here reach 100 dB on both.

At the level you actually listen at

What each one needs from 80 to 105 dB

The Star One is more demanding than 67% of the 567 non-electrostatic models in this database; the K5 than 4%.

dB SPL	K5 power	K5 voltage	Star One power	Star One voltage
80	0.4 µW	3 mV	9.8 µW	25 mV
85	1.3 µW	6 mV	0.03 mW	44 mV
90	4.0 µW	11 mV	0.10 mW	79 mV
95	0.01 mW	19 mV	0.31 mW	0.14 V
100	0.04 mW	33 mV	0.98 mW	0.25 V
105	0.13 mW	59 mV	3.1 mW	0.44 V

What drives both

The cheapest source that satisfies both

Source	Price	Headroom, K5	Headroom, Star One	Output impedance	Noise
JadeAudio JA11	$20	28.2 dB	11.9 dB	0.5 Ω	1.7 µV
FiiO KA11	$29	37.1 dB	20.1 dB	0.7 Ω	1.7 µV
FiiO BTR13	$59	34.1 dB	17.1 dB	0.6 Ω	1.0 µV

Of the 280 sources here, 280 reach 100 dB on both. 51 of them also publish an output impedance low enough for both under the one-eighth rule and a noise figure that stays below the audible-hiss threshold with both.

The cheapest of the 51 is the JadeAudio JA11, at $20. It leaves 28.2 dB of headroom on the K5 and 11.9 dB on the Star One, its output impedance is 0.5 Ω against a one-eighth limit of 3.50 Ω and 8.00 Ω, and its noise figure puts the hiss floor 6 dB and 23 dB below the 20 dB SPL this site treats as the point where a quiet room stops hiding it.

Try any other source.

Frequency response

What each sheet prints, and what it is worth

Model	As printed	Tolerance	Standard
K5	20Hz–20kHz	not printed	not printed
Star One	20Hz - 40kHz	not printed	not printed

EPZ prints 20Hz–20kHz for the K5 and 20Hz - 40kHz for the Star One.

Neither range has a tolerance printed beside it, so a wider range on one sheet is not deeper bass or more treble.

Not a measurement; maker by maker.

Both pages in full

Both have a page of their own. In full: EPZ K5 and EPZ Star One. Each figure on this page is labelled on those pages with where it came from, including the ones EPZ never published — what that maker publishes, counted.