Updated October 2026 · prices checked Oct 10, 2026.
The Question
Sennheiser US lists the HD 600 at $499.95 and the HD 660S2 at $679.95, and both are usually on sale: about $350 and $480 respectively in October 2026. That is roughly a $130 gap for two headphones built on a similar philosophy.
Short answer: the HD 660S2 is the more complete headphone; the HD 600 is still the better value.
The long-standing reference. Most of the HD 660S2's sound for about $130 less on sale.
Deeper bass extension and a smoother treble, with a 4.4 mm balanced cable in the box.
Specs Comparison
| Sennheiser HD 600 | Sennheiser HD 660S2 | |
|---|---|---|
| Impedance | 300Ω | 300Ω |
| Sensitivity | 97 dB/mW (~102 dB/V) | 104 dB/V |
| Weight | 260 g | 260 g |
| Cable | Detachable, dual-sided | Detachable, dual-sided (4.4 mm balanced included) |
| Price (Oct 2026) | ~$350 on sale ($499.95 list) | ~$480 on sale ($679.95 list) |
The practical spec difference: the HD 660S2 ships with a balanced cable as well as the standard one, so it can use a balanced amp output out of the box.
Sound Differences
The points below summarise published frequency-response measurements and owner consensus from Head-Fi and r/headphones, not personal listening notes.
Sub-Bass Extension
This is the HD 660S2’s main advance. The HD 600’s bass rolls off below about 50 Hz: bass guitar is clear, but deep rumble is lighter. The HD 660S2 reaches deeper with more authority.
That matters for electronic, orchestral and organ music. For acoustic guitar, vocal jazz or chamber music, the practical difference is small.
Treble
Owners often describe a slight grain in the HD 600’s treble that some like and others find fatiguing on bright masters. The HD 660S2 is generally described as smoother with similar detail, so it is the more forgiving of the two on harsh recordings.
Midrange
The HD 600 has an upper-midrange presence region around 3 kHz that pushes vocals forward. The HD 660S2 is a little more relaxed there. Plenty of owners prefer the HD 600’s vocal presentation, so this one is down to taste.
Imaging and Soundstage
Owners report marginally better imaging on the HD 660S2. Most say the difference needs direct A/B comparison to pick out.
Source and Amp Requirements
Both are 300Ω. For 110 dB peaks the HD 600 needs about 2.5 V and the HD 660S2 about 2 V. A phone or laptop jack (around 1 V) leaves both short; any decent desktop amp covers both.
| Source (published spec) | HD 600 | HD 660S2 |
|---|---|---|
| Phone / laptop jack (~1 V) | Underpowered | Quieter than it should be |
| FiiO K11 R2R, single-ended (~4 V into 300Ω) | ~+4 dB headroom | ~+6 dB headroom |
| Schiit Magni (Unity) (~11 V into 300Ω) | ~+13 dB headroom | ~+15 dB headroom |
| Topping DX5 II, balanced (6.4 W into 32Ω) | Plenty | Plenty, using the included balanced cable |
Headroom is calculated from the makers’ power ratings, not measured. The DX5 II’s 300Ω figure isn’t published, so the table doesn’t put a number on it.
Best value pairing for the HD 600: DAC and amp in one box.
Best pairing for the HD 660S2: plug in the included 4.4 mm balanced cable and you're done.
For full rankings, see best amp for the HD 600 and best amp for the HD 660S2 . The HD 660S2 review covers that headphone on its own.
Value Analysis
HD 600 path: ~$350 headphone + ~$170 FiiO K11 R2R ≈ $520 total at October 2026 sale prices. One of the best-value reference rigs available.
HD 660S2 path: ~$480 headphone + ~$299 Topping DX5 II ≈ $780 total. A more complete setup with deeper bass and balanced drive. Whether it’s worth about $260 more depends on how much you care about sub-bass and treble smoothness.
Who Should Buy Which
Buy the HD 600 if:
- Budget matters
- You mostly listen to acoustic, jazz, classical strings or vocals
- You want the reference tool engineers have used for decades
- You’re entering the hobby and want maximum value
Buy the HD 660S2 if:
- You listen to music with real low-frequency content
- You want a balanced cable included
- You find the HD 600’s treble edge fatiguing
- The extra cost isn’t a stretch
Skip both if: you need isolation (both are open-back), or you won’t add an amp.
The HD 600 is not obsolete. The HD 660S2 is what the same philosophy looks like with newer materials and a higher price target.
Sennheiser HD 600: See today's price for the Sennheiser HD 600 on Amazon ↗
Sennheiser HD 660S2: See today's price for the Sennheiser HD 660S2 on Amazon ↗
Still deciding between the two classics? See HD 600 vs HD 650 .
