Hello. I would think you should be okay if the headphones are high efficiency. IDT headphones jacks are designed and tested for a 32 ohm load.  I could not find a datasheet for the IDT92HD94 codec but I have one for the IDT92HD93B. Here is a quote from it:

The codec implements both traditional and cap-less headphone outputs. The Microsoft Windows

Logo Program allows up to the equivalent of 100ohms in series. However, an output level of +3dBV

at the pin is required to support 300mV at the jack with a 32ohm load and 1V with a 320 ohm load.

Microsoft allows device and system manufactures to limit output voltages to address EU safety

requirements. (WLP 3.09 - please refer to the latest Windows Logo Program requirements from

Microsoft.) The codec does not support power limiting.

Headphone performance will degrade if more than one port is driving a 32 ohm load.

When they say "The codec does not support power limiting" it means that the audio chip does not internally limit power in order to meet the lower European volume limitations, but they have instructions for computer manufacturers on how to limit volume with resistors or software. I don't know if Dell implements any restrictions on all headphone output or not, but they probably have to do so on models sold in Europe.  If Dell publishes any specifications about that I have not seen them.

Hello. Its difficult to understand what you replied & in my headphone specs there is only sound pressure level (SPL) which is 108 dB (1 kHz / 1V rms) & THD  <0.2% (1 kHz; 100dB SPL. Is this info enough for you to say whether it works on my laptop with out an external sound card ?.

thanks

I'm sorry -- I know you would like a more definitive answer but I can't give one because I don't know if the 15R SE 7520 puts out good volume or not. It should, but sometimes we get complaints about low headphone volume and it is difficult to tell if there is a hardware problem with a particular laptop or if Dell limited the volume intentionally by either hardware or software modification. In Europe for example the volume must be limited as a safety regulation.

Unless someone else can give you a definitive answer I think you won't know for sure if you will be happy with the combination of headphones and laptop until you pair them up and listen.

What I meant in my first reply was that the IDT audio codec is designed for optimal performance (volume and sound quality) with 32 ohm headphones, which is low impedance. I consider 50 ohms to be within the ballpark of low impedance and so I think they would be okay, but not as loud n volume compared to 32 ohm headphones of the same efficiency.

Hello. Its difficult to understand what you replied & in my headphone specs there is only sound pressure level (SPL) which is 108 dB (1 kHz / 1V rms) & THD  <0.2% (1 kHz; 100dB SPL. Is this info enough for you to say whether it works on my laptop with out an external sound card ?.

 When i use my  32 ohm headphones (106 db) there is no volume left to increase in my laptop .So i think there is no point over using more sensitive (112 db) 50 ohm headphones with 32 ohm output headphone jack. Am i right?

Am i right?

I agree. If practical I would take the laptop to a store that sells headphones, even a Radio Shack, and try to find one that pairs up well with the laptop, then shop for one in your preferred brand with the same specifications.

When i use my  32 ohm headphones (106 db) there is no volume left to increase in my laptop

If your volume is not sufficient with your current headphones, you could try different audio drivers and see if you get different results. If you get more volume when you use a different driver it means that your current driver is limiting the headphone volume level. Here are the drivers you could try:

Firstly,

The audio codec manufacturer's driver. That is either Conexant or IDT. The Dell Specifications document for the Inspiron 7520 say it is an IDT 92HD94 codec, and that is what I referred to in my first reply, but when I looked at the Inspiron 7520 downloads page it has a Conexant audio driver. Now I am suspicious that the Specifications document is actually from a different model of Dell laptop. If so I will see if I can get someone at Dell to correct that mistake.

Second,

in Windows 8, 7, and Vista there is a native (non-manufacturer's) audio driver. Currently, you have either the Windows native driver or the manufacturer's driver installed. Whichever one you have, try the other one. To install the manufacturer's driver download it from the Inspiron 7520 downloads page and install it.

To install the native driver, uninstall the manufacturer's driver and reboot. [Go to Control Panel>Uninstall a Program. Find the manufacturer's audio driver then right click on it and uninstall it. Reboot the computer and Windows will install its native audio driver. OR you can go to Device Manager and uninstall the manufacturer's  driver and select the option to delete the files. Reboot.]

Third,

Run the Dell Diagnostics audio test if you have it. You might not have the test for a variety of reasons, but if you can run it it will run in its own non-Windows operating system and will use an audio driver that has no volume limitations. Use the headphones during the tests. If the volume is no louder during the tests than it is when you are in Windows, then your low volume is a hardware limitation of your laptop, either by design or otherwise. [If you do not have the Dell Diagnostics audio tests don't bother using a different diagnostic -- all of the others just use a Windows audio driver during their tests.]

I purchased my laptop two weeks ago & drivers are up to date , i think the problem is with my headphones .Is there any way to know at least the output power of my laptop headphone jack so that i can upgrade my headphones.

thanks

drivers are up to date ,

As you wish, but I was not talking about updating -- was explaining how to attempt to find out if your low volume is due to the hardware or due to limitations placed on the volume by the driver.

Is there any way to know at least the output power of my laptop headphone jack so that i can upgrade my headphones.

Dell does not publish comprehensive audio specifications and I don't know where else you could find the info. How would knowing the output power help you to find louder headphones?

The headphone which im looking for would need 8 mW to output its max efficiency from laptop...

Thanks Jim .