The Thieaudio Monarch MKIV is 10Ω at 100.0 dB (no reference unit printed); the Thieaudio Oracle MKII is 15Ω at 104.0 dB (no figure from the maker at all). This page covers what they ask of an amplifier, not how they sound.
The Monarch MKIV needs 4.0 dB more than the Oracle MKII to reach the same loudness — 1.0 mW against 0.40 mW.
| Specification | Monarch MKIV | Oracle MKII |
|---|---|---|
| Impedance | 10 Ω | 15 Ω |
| Sensitivity | 100.0 dB | 104.0 dB |
| Sensitivity (voltage) | 120.0 dB/V | 122.2 dB/V |
| Power for 100 dB | 1.0 mW | 0.40 mW |
| Voltage for 100 dB | 0.10 V | 77 mV |
| Current for 100 dB | 10.0 mA | 5.2 mA |
| Highest source impedance that leaves them alone (one-eighth rule) | 1.25 Ω | 1.88 Ω |
| Sources that reach 100 dB out of 280 | 280 | 280 |
One caution before reading the rows. Thieaudio Monarch MKIV 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. For Thieaudio Oracle MKII the maker publishes no sensitivity figure at all. The number in the table was collected when this database was first built and has never been traced to a manufacturer document, so treat every row below it as an estimate rather than a specification.
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.
5 sources are low enough in output impedance for the Oracle MKII under the one-eighth rule but not for the Monarch MKIV (FiiO KA13, Schiit Vali 2+, FiiO M11S, 2 more).
2 sources stay below the audible-hiss threshold with the Monarch MKIV but cross it with the Oracle MKII (FiiO BTR11, Rupert Neve RNHP).
280 of the 280 sources here reach 100 dB on both.
The Monarch MKIV is more demanding than 32% of the 567 non-electrostatic models in this database; the Oracle MKII than 24%.
| dB SPL | Monarch MKIV power | Monarch MKIV voltage | Oracle MKII power | Oracle MKII voltage |
|---|---|---|---|---|
| 80 | 0.01 mW | 10 mV | 4.0 µW | 8 mV |
| 85 | 0.03 mW | 18 mV | 0.01 mW | 14 mV |
| 90 | 0.10 mW | 32 mV | 0.04 mW | 24 mV |
| 95 | 0.32 mW | 56 mV | 0.13 mW | 43 mV |
| 100 | 1.0 mW | 0.10 V | 0.40 mW | 77 mV |
| 105 | 3.2 mW | 0.18 V | 1.3 mW | 0.14 V |
| Source | Price | Headroom, Monarch MKIV | Headroom, Oracle MKII | Output impedance | Noise |
|---|---|---|---|---|---|
| JadeAudio JA11 | $20 | 9.7 dB | 15.5 dB | 0.5 Ω | 1.7 µV |
| FiiO KA11 | $29 | 21.9 dB | 27.6 dB | 0.7 Ω | 1.7 µV |
| FiiO BTR13 | $59 | 18.8 dB | 24.5 dB | 0.6 Ω | 1.0 µV |
Of the 280 sources here, 280 reach 100 dB on both. 63 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 63 is the JadeAudio JA11, at $20. It leaves 9.7 dB of headroom on the Monarch MKIV and 15.5 dB on the Oracle MKII, its output impedance is 0.5 Ω against a one-eighth limit of 1.25 Ω and 1.88 Ω, and its noise figure puts the hiss floor 15 dB and 13 dB below the 20 dB SPL this site treats as the point where a quiet room stops hiding it.
| Model | As printed | Tolerance | Standard |
|---|---|---|---|
| Monarch MKIV | 10Hz – 44kHz | not printed | not printed |
| Oracle MKII | nothing printed | — | — |
Thieaudio prints 10Hz – 44kHz for the Monarch MKIV and nothing at all for the Oracle MKII.
Oracle MKII: Thieaudio publishes a measured frequency-response graph for this model on the same page. What it does not publish is a range: there is no row of numbers to read the graph against.
So one side of this comparison has a frequency-response number and the other does not — which changes less than it looks. The range printed for the Monarch MKIV comes with no tolerance beside it, and a range without a ±dB figure says nothing about how loud the headphone is at either end of it: thirty decibels down at the bottom and the sentence would still be true. On the only reading that would have made it a specification, the two sheets say the same amount: nothing.
Not a measurement; maker by maker.
Both have a page of their own. In full: Thieaudio Monarch MKIV and Thieaudio Oracle MKII. Each figure on this page is labelled on those pages with where it came from, including the ones Thieaudio never published — what that maker publishes, counted.