Main trade-off
Sennheiser HD 650
The open design is a poor fit for a shared office.
Head-to-head
Sennheiser HD 650 vs HD 660S2: HD 650 reaches farther, 660S2 adds a 4.4 mm lead
The short answer
Choose HD 660S2 if your amp has a 4.4 mm output and you want the matching cable included. Choose HD 650 for the longer 3 m supplied lead. Both list 260 g and 300 ohms, so the newer model does not buy a lighter headphone or automatically reduce amplifier requirements.
Before you choose
The reasoning and the trade-offs
HD 650 gives 67% more supplied reach
Its 3 m cable is 1.2 m longer than the HD 660S2 leads.
What this is based on
HD 650 supplies a 3 m lead and HD 660S2 supplies 1.8 m leads. (3 - 1.8) / 1.8 × 100 = 66.7% more reach from the longer supplied cable.
Main trade-off
Sennheiser HD 660S2
The supplied cables are shorter than the HD 600 and HD 650 leads.
Sennheiser HD 650
- Choose it for
- You need a 3 m lead to reach the amplifier.
- You only use conventional 3.5 or 6.3 mm outputs.
- Main trade-off
- The open design is a poor fit for a shared office.
Sennheiser HD 660S2
- Choose it for
- You want a 4.4 mm balanced cable in the box.
- A 1.8 m lead comfortably reaches your desk source.
- Main trade-off
- The supplied cables are shorter than the HD 600 and HD 650 leads.
About this comparison
Compare HD 650 and HD 660S2 by the included balanced cable, desk reach and shared 300-ohm setup. Find out which package fits your amplifier.
Choose HD 660S2 if your amp has a 4.4 mm output and you want the matching cable included. Choose HD 650 for the longer 3 m supplied lead. Both list 260 g and 300 ohms, so the newer model does not buy a lighter headphone or automatically reduce amplifier requirements.
Winner by situation
Start with what you need it to do
Amp has a 4.4 mm output you want to use
HD 660S2 supplies the matching cable.
- Sennheiser HD 650
- Good
- Sennheiser HD 660S2
- Better fit
Amp is 2.5 m along the cable route
HD 650 reaches that route, while 1.8 m is short.
- Sennheiser HD 650
- Better fit
- Sennheiser HD 660S2
- Caution
You want less headphone weight
Both list 260 g.
- Sennheiser HD 650
- Similar
- Sennheiser HD 660S2
- Similar
A shared or noisy room
The open construction does not change between them.
- Sennheiser HD 650
- Not suitable
- Sennheiser HD 660S2
- Not suitable
What matters in practice
The differences that matter
HD 650 gives 67% more supplied reach
Its 3 m cable is 1.2 m longer than the HD 660S2 leads.
How we reached this conclusion
HD 650 supplies a 3 m lead and HD 660S2 supplies 1.8 m leads. (3 - 1.8) / 1.8 × 100 = 66.7% more reach from the longer supplied cable.
A balanced cable is an accessory saving, not a sound promise
HD 660S2 includes a 4.4 mm lead that HD 650 buyers would need to obtain separately for a compatible amp.
How we reached this conclusion
Official package lists show a 4.4 mm cable only with HD 660S2.
The published weight and impedance are tied
Neither physical weight nor nominal impedance creates an upgrade reason.
How we reached this conclusion
Both models are listed at 260 g and 300 ohms.
Check your own setup
Which headphones work with the way you listen?
Start with the way you listen. USB charging is not the same as USB audio, and some headphones need power even with a cable. These choices are examples until you apply yours.
Sennheiser HD 650
Does not meet these checksThis model does not play over Bluetooth.
Sennheiser HD 660S2
Does not meet these checksThis model does not play over Bluetooth.
Battery figures are manufacturer claims for the stated mode, not measured travel time. Volume, codec, calls and battery age change runtime. Closed earcups can still leak sound. Weight alone does not predict comfort. USB audio needs a compatible source and cable. This check does not assess sound quality, microphone quality or amplifier power.
Choice A
Sennheiser, HD 650
HD 650
A battery-free open-back headphone with a 3 m lead and replaceable parts. It suits a quiet home setup much better than a commute.
- Best matched use
- Long listening sessions at a home hi-fi setup
Checked facts
- The listed weight is 260 g.
- The supplied detachable cable is 3 m long with a 6.35 mm plug and 3.5 mm adapter.
- Nominal impedance is 300 ohms.
Choice B
Sennheiser, HD 660S2
HD 660S2
A wired open-back pair supplied with both 6.3 mm and 4.4 mm cables. Useful when the headphone amp already has a balanced output.
- Best matched use
- A quiet desk with both conventional and balanced headphone outputs
Checked facts
- The package includes separate 1.8 m 6.3 mm and 4.4 mm cables.
- The manufacturer specifies 260 g and 300 ohms.
- The cups are open and the headphone requires no charging.
Meaningful differences
What changes the fit
| What changes | Sennheiser HD 650 | Sennheiser HD 660S2 | Why it matters |
|---|---|---|---|
| Longest supplied lead | 3 m | 1.8 m | HD 650 offers 1.2 m more reach. |
| 4.4 mm cable in the box | No | Yes | HD 660S2 avoids a separate compatible balanced-cable purchase. |
| Conventional cable | 6.35 mm with 3.5 mm adapter | 6.3 mm with 3.5 mm adapter | Both can connect to common analog headphone outputs. |
| Weight | 260 g | 260 g | Neither is a lighter choice by the listed figures. |
| Impedance | 300 ohms | 300 ohms | A higher model number does not remove the need to check your source. |
| Construction | Open-back | Open-back | Both require a quiet room where leakage is acceptable. |
What you give up
Every choice has a cost
If you choose Sennheiser HD 650
- There is no microphone or Bluetooth connection.
If you choose Sennheiser HD 660S2
- A balanced connector is not a promise of audible improvement.
Recommendation switch
The decision flips if...
You need a 3 m lead to reach the amplifier.
Choose Sennheiser HD 650. HD 650 gives a listening chair more freedom because its lead is 3 m long. An extension can change that for HD 660S2, but it is another item and connection to plan.
You want a 4.4 mm balanced cable in the box.
Choose Sennheiser HD 660S2. A 4.4 mm balanced lead is useful only with a compatible balanced headphone output. Do not connect it through an arbitrary adapter that shorts amplifier outputs.
What matters in practice
How to make the call
Long cable routes favor the older package
HD 650 gives a listening chair more freedom because its lead is 3 m long. An extension can change that for HD 660S2, but it is another item and connection to plan.
Choose the cable your amp actually supports
A 4.4 mm balanced lead is useful only with a compatible balanced headphone output. Do not connect it through an arbitrary adapter that shorts amplifier outputs.
Tuning preference still needs a listening decision
The same listed weight and impedance do not mean identical sound. They do show that the basic physical setup is not a reason to promise an automatic upgrade.
What this comparison cannot tell you
- Balanced output is not inherently an audible improvement.
- No listening test or amplifier-performance measurement is claimed.
What the facts say
What the comparison shows
Useful conclusions from the current headphones comparison, followed by the checked facts used to reach them.
Compared set
21 of 60 models checked match every need here: “I want music when the battery is empty”, “I plug into a headphone jack”, and “I do not want another thing to charge”.
21 matching models from 60 checkedSee the checked facts and calculation notes
Match countThe count uses the current product-to-need assignments for “I want music when the battery is empty”, “I plug into a headphone jack”, and “I do not want another thing to charge”. A need with no documented match does not count.
| Product | Needs matched | Checked facts | Source records |
|---|---|---|---|
| Sennheiser HD 650 |
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| Sennheiser HD 660S2 |
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Ready to choose?
Check the price. Read the owner reviews.
Open either model on Amazon to check the current price, customer reviews and delivery options.
Sennheiser HD 650
You need a 3 m lead to reach the amplifier.
See price & reviews on AmazonSennheiser HD 660S2
You want a 4.4 mm balanced cable in the box.
See price & reviews on AmazonLinks open in a new tab.