The catch
Sennheiser HD 650
A shared office is no place for an open design.
Side by side
Sennheiser HD 650 vs HD 660S2 Guide: Reach is longer on HD 650, and 660S2 adds a 4.4 mm lead
Quick verdict
HD 660S2 is the pick if your amp has a 4.4 mm output and you want the matching cable included. HD 650 is the pick for the longer 3 m supplied lead. Both list 260 g and 300 ohms, so the newer model gets you neither a lighter headphone nor automatically lower amplifier requirements.
Before you buy
Why, and what it costs you
HD 650’s supplied cable reaches 67% farther
The 3 m cable beats the HD 660S2 leads by 1.2 m.
Where this comes from
HD 650 comes with a 3 m lead, while HD 660S2 comes with 1.8 m leads. That makes the longer supplied cable reach (3 - 1.8) / 1.8 × 100 = 66.7% farther.
The catch
Sennheiser HD 660S2
Its included cables fall short of the HD 600 and HD 650 leads in length.
Sennheiser HD 650
- Why pick it
- Reaching the amplifier takes a 3 m lead.
- Conventional 3.5 or 6.3 mm outputs are all you use.
- The catch
- A shared office is no place for an open design.
Sennheiser HD 660S2
- Why pick it
- A 4.4 mm balanced cable in the box is what you want.
- Your desk source is within easy reach of a 1.8 m lead.
- The catch
- Its included cables fall short of the HD 600 and HD 650 leads in length.
We may earn a commission from qualifying Amazon purchases. How we make money
What this page compares
HD 650 and HD 660S2 compared on the included balanced cable, desk reach and the 300-ohm setup they share, so you can see which package suits your amplifier.
HD 660S2 is the pick if your amp has a 4.4 mm output and you want the matching cable included. HD 650 is the pick for the longer 3 m supplied lead. Both list 260 g and 300 ohms, so the newer model gets you neither a lighter headphone nor automatically lower amplifier requirements.
Which one fits
Pick the situations that sound like you
You want to use your amp’s 4.4 mm output
The matching cable comes with HD 660S2.
- Sennheiser HD 650
- Good
- Sennheiser HD 660S2
- Better fit
The cable route to your amp is 2.5 m
The HD 650 lead covers that route, while 1.8 m falls short.
- Sennheiser HD 650
- Better fit
- Sennheiser HD 660S2
- Caution
A lighter headphone matters to you
Each lists 260 g.
- Sennheiser HD 650
- Similar
- Sennheiser HD 660S2
- Similar
A shared room, or a loud one
Both share the same open construction.
- Sennheiser HD 650
- Not suitable
- Sennheiser HD 660S2
- Not suitable
In practice
Differences you will notice
HD 650’s supplied cable reaches 67% farther
The 3 m cable beats the HD 660S2 leads by 1.2 m.
How we worked this out
HD 650 comes with a 3 m lead, while HD 660S2 comes with 1.8 m leads. That makes the longer supplied cable reach (3 - 1.8) / 1.8 × 100 = 66.7% farther.
A balanced cable saves on accessories and promises nothing for sound
Buyers of HD 650 with a compatible amp must source a 4.4 mm lead on their own, since HD 660S2 includes one.
How we worked this out
Only HD 660S2 appears with a 4.4 mm cable in the official package lists.
Published weight and impedance come out equal
Neither the weight nor the nominal impedance gives you a reason to upgrade.
How we worked this out
260 g and 300 ohms is the listing for each model.
Plug in your setup
Which headphones suit the way you listen?
Start with how you listen. Charging over USB is not the same as playing audio over USB, and some headphones need power even on a cable. These answers are placeholders until you apply your own.
Sennheiser HD 650
Fails these checksThis model cannot play over Bluetooth.
Sennheiser HD 660S2
Fails these checksThis model cannot play over Bluetooth.
Battery figures are maker claims for the stated mode. They do not reflect measured travel time. Volume, codec, calls and battery age all change runtime. Closed earcups can still leak some sound. Weight alone does not predict comfort. USB audio needs a compatible source and cable. This check does not judge sound quality, mic quality or amplifier power.
Option A
Sennheiser, HD 650
HD 650
This open-back headphone needs no battery, comes with a 3 m lead and has replaceable parts. A quiet home setup is a far better match for it than a commute.
- Best for
- Extended sessions with a hi-fi system at home
Facts we checked
- Its listed weight comes to 260 g.
- A detachable 3 m cable is supplied, with a 6.35 mm plug and a 3.5 mm adapter.
- Impedance is nominally 300 ohms.
Option B
Sennheiser, HD 660S2
HD 660S2
This wired open-back pair ships with a 6.3 mm cable and a 4.4 mm cable. It helps if your headphone amp already has a balanced output.
- Best for
- Quiet-desk use with conventional and balanced headphone outputs both available
Facts we checked
- In the package are separate 1.8 m 6.3 mm and 4.4 mm cables.
- The manufacturer's spec is 260 g and 300 ohms.
- No charging is needed, and the cups are open.
Spec by spec
Where they really differ
| Spec | Sennheiser HD 650 | Sennheiser HD 660S2 | In practice |
|---|---|---|---|
| Longest supplied lead | 3 m | 1.8 m | You get 1.2 m more reach with HD 650. |
| 4.4 mm cable in the box | No | Yes | With HD 660S2 you do not have to buy a compatible balanced cable separately. |
| Conventional cable | 6.35 mm with 3.5 mm adapter | 6.3 mm with 3.5 mm adapter | Common analog headphone outputs are no problem for either one. |
| Weight | 260 g | 260 g | By the listed figures, neither is the lighter option. |
| Impedance | 300 ohms | 300 ohms | A bigger model number does not excuse you from checking your source. |
| Construction | Open-back | Open-back | Each needs a quiet room in which sound leakage is fine. |
Trade-offs
What each pick costs you
With Sennheiser HD 650
- It has neither a microphone nor Bluetooth.
With Sennheiser HD 660S2
- A balanced connector does not guarantee you will hear an improvement.
Change of plan
When the answer changes
Reaching the amplifier takes a 3 m lead.
Go with Sennheiser HD 650. A listening chair gets more freedom with HD 650 because its lead is 3 m long. An extension can fix that for HD 660S2, but it is one more item and connection to plan for.
A 4.4 mm balanced cable in the box is what you want.
Go with Sennheiser HD 660S2. You get value from a 4.4 mm balanced lead only with a compatible balanced headphone output. Never connect it through an arbitrary adapter that shorts amplifier outputs.
Decision guide
How to decide
If your amp has a 4.4 mm output and you want the matching cable included, pick HD 660S2. If you want the longer 3 m supplied lead, pick HD 650. Both list 260 g and 300 ohms, so the newer model does not give you a lighter headphone or lower amplifier requirements automatically.
The older package suits long cable runs
A listening chair gets more freedom with HD 650 because its lead is 3 m long. An extension can fix that for HD 660S2, but it is one more item and connection to plan for.
Go for the cable your amp can use
You get value from a 4.4 mm balanced lead only with a compatible balanced headphone output. Never connect it through an arbitrary adapter that shorts amplifier outputs.
Tuning preference still comes down to listening
Identical listed weight and impedance do not make the sound identical. They do show that the basic physical setup gives no grounds to promise an automatic upgrade.
What this page can’t tell you
- A balanced output is not an audible improvement by nature.
- This page claims no listening test and no measurement of amplifier performance.
By the numbers
What the data shows
What we found across the headphones we compare, plus the checked facts behind each finding.
How many fit
21 of the 60 models checked meet every need here: “I want music even with a dead battery”, “I connect to a headphone jack”, and “I do not want something else to charge”.
21 models fit, out of 60 checkedShow the facts and the math
How we countedThe count uses each product's current fit ratings for “I want music even with a dead battery”, “I connect to a headphone jack”, and “I do not want something else to charge”. A need with no documented match is not counted.
| Product | Needs it meets | Facts we checked | Sources |
|---|---|---|---|
| Sennheiser HD 650 |
|
|
|
| Sennheiser HD 660S2 |
|
|
|
Ready to buy
See today’s price and what owners say
Open either model on Amazon for the current price, customer reviews and delivery options.
Sennheiser HD 650
Reaching the amplifier takes a 3 m lead.
See price & reviews on AmazonSennheiser HD 660S2
A 4.4 mm balanced cable in the box is what you want.
See price & reviews on AmazonEach link opens in a new tab.
We may earn a commission from qualifying Amazon purchases. How we make money