"With this amount of money, I would rather go for a wired IEM which sounds better."
I believe a lot of audio lovers encounter this from their friends when they purchased a premium wireless headphones such as Bowers & Wilkins PX or Sony WH-1000XM3.
A lot of people believe that wired devices sound better as compared to wireless devices. True, if you are comparing Sony WH-1000XM3 with TOTL IEMs like Campfire Audio Solaris or Empire Ears Phantom.
No doubts, the latter is better in most of the aspect but this is not a valid comparison.
To compare between wired and wireless devices, the first aspect to take note of is the price. The two items that you are comparing should be at least in the same price range. For an example, to compare the performances of Sony WH-1000XM3 which is retailing at SGD549.00, you can choose to compare with FiiO FA7, which is retailing at SGD499.00. Now the comparison is valid. In this scenario, wired devices could potentially sound better than the wireless device but a lot of other factors are affecting this such as recording quality and Bluetooth codec used.
Let's take a look at an example:
I am an Android user and my phone support LDAC codec. I connect to Sony WH-1000XM3 on LDAC and I play loseless files such as 16 bit/44.1kHz FLAC. LDAC able to support transmission speed at 990kbps. Potentially my files will not be compressed during the transmission. The Digital to Analogue converter (DAC) and amplifier in WH-1000XM3 decodes and amplifies the digital signal received. Perfect and sounds good.
Now I plug the single-ended FA7 into my phones and I play the same song. The transmission speed is no longer an issue here but the DAC and amplifier in the phone will play an important role here - Do they have the capability to decode the recording flawlessly? The final sound quality might be constrained if the DAC and amplifier in the phone cannot perform up to the standard. In this scenario, wireless device can sound better than the wired device because some factors are pulling the performance back.
In order for a wired device to sounds good, a lot of factors need to be considered. As mentioned in the previous example, the DAC and amplifier played an essential role in determining the sound quality. A dedicated DAC and amplifier such as Chord Mojo can rectify the issue. Dedicated DAC and amplifier are specially designed and tuned to yield the the best audio quality. Unlike integrated DAC and amplifier in the phone - multitasking. Phone calls, watching videos, listening to WhatsApp voice messages and everything related to voices and sounds. Beside multitasking, dedicated DAC and amplifiers modules normally cost more as compared to the integrated one. To reduce the manufacturing cost, integrated module will be a better choice without a doubt.
"Will my wireless headphones sound better if I connect it using wire?"
This is another common issue I came across. There is no absolute answer to this question. Again, scenario and case by case basis but in most of the cases, wireless option is more favorable.
If you phone support Hi-Res codec such as aptX HD or LDAC and you have a library of loseless tracks, go for the wireless option. Your phone DAC and amplifier might not be as good as the one used in the headphones. The dedicated module equipped in the headphones are specially tuned to achieve certain music quality. To fully unleash the potential, you will need to rely on the module equipped. For most of the Android phones now in the market, aptX HD and LDAC should be common.
Now the issue rises. How about iPhone?
iPhone is using AAC codec which is specially designed for iPhone. AAC codec does not have the capability to support fast transmission speed like aptX or LDAC. The good news, is despite being slightly lower throughput, AAC is widely praised among lossy algorithms as a step up from Subband Codec (SBC) and there is a wide variety of compatible headphones. If you’re using a pair of AAC-compatible headphones, you’re theoretically getting no loss in audio quality from your stored AAC files (the iTunes standard) or streaming from the Apple Music service. So, for iPhone users to obtain optimum configuration, use an AAC-compatible headphones with AAC files.
If you are thinking using the wireless device with a wire connected to your phone might improve the sound quality, you might need to think twice. As mentioned in the previous section, wired configuration will be highly dependent to your phone DAC and amplifier performance. The integrated module might pull back the performance of the headphone despite the transmission speed is faster. Unless you have a dedicated DAC and amplifier, wire configuration is not recommended. The wire is provided for 2 scenarios - battery of the headphone is flat or Bluetooth is not available like in the plane. If Bluetooth is available and battery is charged, wireless is always the best option.
Conclusion
There are more factors can be discussed about Bluetooth headphones performance but these are the very essential factors that every user should aware of. Bluetooth has been evolving fast and a lot of bottlenecks are removed with the evolution. In this era, Bluetooth headphone is the one you should go for if you are looking for all-in-one solution. For those fever fans, go for wired configuration which gives you more liberty and freedom in upgrade and tuning in the sound quality. Happy listening!