Short answer
Both are portable players, $919 against $898.
The Shanling M6 Ultra reaches 100 dB on 565 of the 567 models here, the Sony NW-ZX707 on 550.
| Specification | Shanling M6 Ultra | Sony NW-ZX707 |
|---|---|---|
| Power into 32Ω | 240 mW | 25 mW |
| Power into 150Ω | 51 mW | 5.3 mW |
| Power into 300Ω | 26 mW | 2.7 mW |
| Power into 600Ω | 13 mW | 1.3 mW |
| Output impedance | 1.0 Ω | not published |
| Output noise | not published | not published |
| Price | $919 | $898 |
| Headphones it reaches 100 dB on out of 567 | 565 | 550 |
Not published means the maker leaves it out, so that axis cannot be compared.
| Balanced | Shanling M6 Ultra | Sony NW-ZX707 |
|---|---|---|
| Socket | 4.4mm | 4.4mm |
| Power into 32Ω | 720 mW | 115 mW derived |
| Power into 300Ω | 77 mW derived | 12 mW derived |
| Output impedance | 1.0 Ω | not published |
| Output noise | not published | not published |
| Headphones it reaches 100 dB on out of 567 | 566 | 561 |
Through the balanced sockets the Shanling M6 Ultra reaches 100 dB on 566 of the 567 models here and the Sony NW-ZX707 on 561. Derived figures are worked out from the loads the maker did publish.
| Load | Shanling M6 Ultra | Sony NW-ZX707 |
|---|---|---|
| 32 Ω | Published | Derived |
| 150 Ω | Derived | Derived |
| 300 Ω | Derived | Derived |
| 600 Ω | Derived | Derived |
Only one of these two columns starts from a power rating. Shanling M6 Ultra publishes one at 32 Ω; Sony NW-ZX707 publishes none at any of these four loads, so its column is worked out from power it published at other loads. Both are arithmetic on a maker’s own figures rather than guesses, and the method used for the Sony NW-ZX707 understates rather than flatters — but at 32 Ω is the only load here at which its maker can be held to a figure.
15 headphones reach 100 dB on the Shanling M6 Ultra but not on the Sony NW-ZX707 — Audio-Technica ATH-R70xa, Beyerdynamic DT 880 Edition (600Ω), Beyerdynamic DT 990 Edition (600Ω), 12 more.
550 of the 567 models here reach 100 dB on both.
Headroom is at a 100 dB SPL peak.
The widest gap on the list is the Audio-Technica ATH-R70X: Shanling M6 Ultra has +10 dB of headroom there against +0 dB. 10 dB is about 9.7 times the power, which matters for peaks rather than for how loud the music sits.
The hiss columns are empty for Shanling M6 Ultra and Sony NW-ZX707 because neither maker publishes no output noise figure.
| Headphone | Impedance | Needs | Shanling M6 Ultra headroom | Sony NW-ZX707 headroom | Shanling M6 Ultra hiss | Sony NW-ZX707 hiss |
|---|---|---|---|---|---|---|
| Shure SE846 | 9 Ω | 0.04 mW | +32 dB | +28 dB | not published | not published |
| Campfire Audio Andromeda 2020 | 9 Ω | 4.0 mW | +12 dB | +8 dB | not published | not published |
| Audeze LCD-2 Classic | 70 Ω | 0.79 mW | +21 dB | +12 dB | not published | not published |
| Beyerdynamic DT 1990 Pro (250Ω) | 250 Ω | 0.63 mW | +17 dB | +7 dB | not published | not published |
| HiFiMAN HE400se | 25 Ω | 7.9 mW | +14 dB | +6 dB | not published | not published |
| Audio-Technica ATH-R70X | 470 Ω | 1.6 mW | +10 dB | +0 dB | not published | not published |
| Sennheiser HD 600 | 300 Ω | 6.6 mW | +6 dB | -4 dB | not published | not published |
| HiFiMAN Susvara | 60 Ω | 50 mW | +4 dB | -6 dB | not published | not published |
The Shanling M6 Ultra costs $21 more than the Sony NW-ZX707. Out of the 567 models here, that difference buys 15 more models driven to 100 dB.
Nothing runs the other way: there is no axis here on which the cheaper of the two does better.
Only published figures count here; blank axes are counted separately.
Each in full: Shanling M6 Ultra and Sony NW-ZX707.