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- Table of Contents
- Top
- Main Differences
- Design
- Sound
- Isolation
- Microphone
- Active Features
- Connectivity
- Comments
Superlux HD 681 vs Superlux HD 668B
Side-by-Side Comparison
Products
Superlux HD 681
Superlux HD 668B
Tested using Methodology v1.8
Updated May 27, 2025 08:01 PM
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Amazon.comTested using Methodology v1.5
Updated Apr 26, 2022 08:51 PM
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Amazon.com
TypeOver-ear
Noise CancellingNo
EnclosureSemi-Open
WirelessNo
TransducerDynamic
MicNo
TypeOver-ear
Noise CancellingNo
EnclosureSemi-Open
WirelessNo
TransducerDynamic
MicNo
Variants
- HD 681
- HD 668B
Our Verdict
Superlux HD 681
Superlux HD 668B
The Superlux HD 668B and the Superlux HD 681 are both very good headphones if you like a balanced sound. While they both can sound quite harsh and sharp, the HD 668B feature a slightly bassier default sound. While both have a similarly disappointing build quality, the HD 681 are a fair bit more comfortable to wear.
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Standard
HD 681
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HD 668B
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HD 681
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HD 668B
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HD 681
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HD 668B
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HD 681
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HD 668B
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HD 681
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HD 668B
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Full Comparison
Design
Style
Design Picture 2
Type
Over-ear
Over-ear
Enclosure
Semi-Open
Semi-Open
Wireless
No
No
Transducer
Dynamic
Dynamic
Comfort
7.5
6.0
Comfort Picture
Weight
0.5 lbs
0.51 lbs
Clamping Force
0.9 lbs
1.2 lbs
Controls
0.0
0.0
Controls Picture
OS Compatibility
No Controls
No Controls
Ease Of Use
No Controls
No Controls
Feedback
No Controls
No Controls
Call/Music Control
No
No
Volume Control
No
No
Microphone Control
No
No
Channel Mixing
No
No
Noise Cancelling Control
No
No
Talk-Through
No
No
Additional Controls
No
No
Breathability
6.8
6.8
Breathability After Picture
Avg.Temp.Difference
4.8 °C
4.8 °C
Portability
5.4
5.2
Portability Picture
L
8.0" (20.3 cm)
9.0" (22.9 cm)
W
7.2" (18.3 cm)
7.1" (18.0 cm)
H
3.5" (8.9 cm)
4.1" (10.4 cm)
Volume
201.00 in³ (3,293.79 cm³)
262.00 in³ (4,293.39 cm³)
Transmitter Required
No
No
Case
5.5
5.5
Case Picture
Type
No case
Pouch
L
N/A
N/A
W
N/A
N/A
H
N/A
N/A
Volume
N/A
N/A
Build Quality
5.5
5.5
Build Quality Picture
Stability
6.0
6.5
Stability Picture
Headshots 1
Angled Picture
Side Picture
Headshots 2
Front Picture
Rear Picture
Top
Top Picture
In The Box
In The Box Picture
Sound
Sound Profile
Sound Profile
Normalization Frequency
1,500 Hz
Bass Amount
-4.2 dB
-1.62 dB
Treble Amount
1.6 dB
0.34 dB
Frequency Response Consistency
7.8
7.5
Consistency L
Consistency R
Avg. Std. Deviation
0.44 dB
0.49 dB
Raw Frequency Response
Bass Profile: Target Compliance
7.4
7.9
Bass Profile: Target Compliance
RMS Deviation From Target
5.5 dB
2.86 dB
Low-Frequency Extension
27.29 Hz
32.68 Hz
Low Bass
-7.23 dB
-2.72 dB
Mid Bass
-2.34 dB
3 dB
High Bass
-1.53 dB
3.17 dB
Mid-Range Profile: Target Compliance
9.1
9.1
Mid-Range Profile: Target Compliance
RMS Deviation From Target
1.01 dB
1.25 dB
Low Mid
-1.12 dB
1.47 dB
Mid-Mid
-0.96 dB
0 dB
High Mid
0.38 dB
0.74 dB
Treble Profile: Target Compliance
6.9
7.4
Treble Profile: Target Compliance
RMS Deviation From Target
3.39 dB
3.93 dB
Low Treble
-0.24 dB
0.37 dB
Mid Treble
4.05 dB
5.18 dB
High Treble
-1.81 dB
-0.9 dB
Peaks/Dips
7.7
7.4
Peaks/Dips Graph
Peaks
1.1 dB
1.62 dB
Dips
2.39 dB
1.41 dB
Imaging
8.1
8.5
Phase Response Mismatch
Weighted Group Delay
0.26
0.33
Weighted Phase Mismatch
12.02
9.13
Weighted Amplitude Mismatch
0.76
0.31
Weighted Frequency Mismatch
1.71
1.75
Passive Soundstage
7.8
7.6
PRTF Accuracy (Std. Dev.)
1.58 dB
1.64 dB
PRTF Size (Avg.)
6.36 dB
7.04 dB
PRTF Distance
11.68 dB
11.79 dB
Openness
9.2
9.1
Acoustic Space Excitation
6.7
6.4
Virtual Soundstage
0.0
0.0
Virtual Soundstage
Head Modeling
No
No
Speaker Modeling
No
No
Room Ambience
No
No
Head Tracking
No
No
Virtual Surround
No App
No App
Weighted Harmonic Distortion
7.6
8.0
Weighted Harmonic Distortion
WHD @ 90
0.145
0.100
WHD @ 100
0.313
0.189
Test Settings
Firmware
No Firmware
No Firmware
Power
Passive
Passive
Connection
Wired
Wired
Codec
PCM, 24-bit, 48kHz
PCM, 24-bit, 48kHz
Test Instrument
Audio Precision APx517B
EQ
No EQ
No EQ
ANC
No ANC
No ANC
Tip/Pad
Default
Default
Microphone
No Microphone
No Microphone
Isolation
Noise Isolation - Full Range
2.6
2.0
Noise Isolation - Full Range Graph
Noise Cancelling
No
No
Overall Attenuation
-5.95 dB
-6.69 dB
Isolation Audio
Bass
0.18 dB
0.16 dB
Mid
-0.14 dB
-0.23 dB
Treble
-19.85 dB
-19.73 dB
Noise Isolation - Common Scenarios
2.8
Noise Isolation - Common Scenarios Graph
Airplane Noise Attenuation
-5.04 dB
Airplane Noise Isolation Audio
Office Noise Attenuation
-5.31 dB
Office Noise Isolation Audio
Street Noise Attenuation
-5.59 dB
Street Noise Isolation Audio
Noise Isolation - Voice Handling
Female Voice 1
Male Voice 1
Female Voice 2
Male Voice 2
ANC Wind Handling
ANC Wind Handling Graph
ANC Wind Noise
N/A
Leakage
4.3
4.5
Leakage Audio
Overall Leakage @ 1ft
52.9 dB
51.95 dB
Microphone
Microphone Style
Integrated
No
No
In-Line
No
No
Boom
No
No
Detachable Boom
No
No
Mic
No
No
Recording Quality
0.0
0.0
Microphone Frequency Response
Recorded Speech
N/A
N/A
LFE
N/A
N/A
FR Std. Dev.
N/A
N/A
HFE
N/A
N/A
Weighted THD
N/A
N/A
Gain
N/A
N/A
Noise Handling
0.0
0.0
SpNR
SpNR
N/A
N/A
Noise Gate
No
No
Speech + Pink Noise Handling
N/A
N/A
Speech + Pink Noise Audio Sample
N/A
N/A
Speech + Subway Noise Handling
N/A
N/A
Speech + Subway Noise Audio Sample
N/A
N/A
Active Features
Battery
0.0
0.0
Battery Type
No Battery
No Battery
Continuous Battery Life
N/A
N/A
Additional Charges
N/A
N/A
Total Battery Life
N/A
N/A
Charge Time
N/A
N/A
Power-Saving Feature
No
No
Audio While Charging
No
No
Passive Playback
Passive Headphone
Passive Headphone
Charging Port
None
None
App Support
0.0
0.0
App Picture
App Name
No App
No App
iOS
No
No
Android
No
No
macOS
No
No
Windows
No
No
Equalizer
No
No
ANC Control
No
No
Mic Control
No
No
Room Effects
No
No
Playback Control
No
No
Button Mapping
No
No
Surround Support
No
No
Connectivity
Wired Connection
9.1
9.5
Cable Picture
Analog Audio
Yes
Yes
USB Audio
No
No
Detachable
No
Yes
Length
8.00 ft (2.44 m)
10.00 ft (3.05 m)
Connector
1/8" TRS
1/8" TRS
Latency - Analog
0.2 ms
Latency - USB
N/A
0 ms
Recorded Latency
Recorded Latency Connection
Analog
Bluetooth Connection
0.0
0.0
Bluetooth Version
No Bluetooth
No Bluetooth
Multi-Device Pairing
No
No
NFC Pairing
No
Quick Pair (Android)
No
Quick Pair (iOS)
No
Line Of Sight Range
N/A
N/A
Latency - SBC
N/A
N/A
Latency - aptX
N/A
N/A
Latency - aptX Adaptive (High Quality)
N/A
Latency - aptX Adaptive (Low Latency)
N/A
Latency - LDAC
N/A
Recorded Latency
N/A
Recorded Latency Codec
No Bluetooth Audio
AAC Support
No
PC Latency (aptX HD)
N/A
PC Latency (aptX-LL)
N/A
iOS Latency
N/A
Android Latency
N/A
Wireless Connection (Dongle)
0.0
0.0
Line Of Sight Range
N/A
N/A
Latency - Dongle
N/A
N/A
Recorded Latency
N/A
PC Compatibility
Analog
Audio Only
Audio Only
Wired USB
No
No
Non-BT Wireless
No
No
PlayStation Compatibility
PS4 Analog
Audio Only
Audio Only
PS4 Wired USB
No
No
PS4 Non-BT Wireless
No
No
PS5 Analog
Audio Only
Audio Only
PS5 Wired USB
No
No
PS5 Non-BT Wireless
No
No
Xbox Compatibility
Xbox One Analog
Audio Only
Audio Only
Xbox One Wired USB
No
No
Xbox One Non-BT Wireless
No
No
Xbox Series X|S Analog
Audio Only
Audio Only
Xbox Series X|S Wired USB
No
No
Xbox Series X|S Non-BT Wireless
No
No
Base/Dock
0.0
0.0
Type
No Base/Dock
No Base/Dock
USB Input
No
No
Line In
No
No
Line Out
No
No
Optical Input
No
No
RCA Input
No
No
Dock Charging
No
No
Power Supply
No Base/Dock
No Base/Dock
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Standard
HD 681
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HD 668B
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HD 681
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HD 668B
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HD 681
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HD 668B
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HD 681
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HD 668B
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HD 681
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HD 668B
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Superlux HD 681
Superlux HD 668B
Comments
Superlux HD 668B vs Superlux HD 681: Main Discussion
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