Yes, it's definitely possible. There is a huge market for after market sound cards. I use one by AVID called the Mbox Pro, which uses a FireWire connection and has about 8 inputs or so. Also, it came with a copy of a software DAW called Pro Tools.
There are many other different brands & devices, most of which support USB connectivity. FYI: You are more likely to find this kind of thing for sale at a musical instrument retailer than at a tech hardware store. Also, there are heaps of different music (&) production related forums online, including some Stack Exchange sites you might like to check out.
To get you started, some popular brands that I've used in the past that you might like to check out are: Behringer, Mackie, Tascam, Lexicon, Akai, M-Audio, Alesis, PreSonus, Focusrite, RME, MOTU & Native Instruments.. (and more..)
Most audio production software is currently designed and marketed towards Windows & Macintosh owners/users. sometimes, however, I still use the free & open-source, Linux-compatible DAW classics Audacity & Rosegarden. There is also Ardour for UNIX which is almost free and quite well maintained. Bitwig is not free at all but does support Linux, resembles the ever-popular Ableton Live, and is generally very nice. If you're not dedicated to Linux there are heaps of popular (some of which are quite expensive) commercial software DAWs like: FL-Studio, Cubase, Logic, GarageBand, Reaper, Acid, Reason, Ignite.. (just to name a few..)
I hope you find at least some of this information useful.
Good luck!
What type of sound card do you currently have? If you have three effective inputs now (line in, mic) you won't be able to send more input into the sound card without splitting the inputs or upgrading your hardware. I.e., sending two inputs into one port by using a y-connector, but which will reduce recording quality and you'll have to manage both inputs on the same channel. Do you have an external mixer board? – Daedalus – 2015-09-16T14:49:50.193
Yup i have mixer board but it will give only stereo output. i want to give 8 sound signal to my pc. speccy shows realtek high defination audio for recording devices. Can i add another sound card to my pc which have 8 inputs for mic?? – mandaliya saurin – 2015-09-16T18:16:08.393
Certainly, but your chance of finding a sound card with eight inputs is slim to none. Short of giving specific product recommendations, for a more effective setup I recommend using a USB-connected external device, such as one of the external boxes by M-Audio or Lexicon Alpha, etc. Alternatively, you can get a USB mixer that won't require an input other than USB and can be easily managed with a digital audio workstation. – Daedalus – 2015-09-16T18:21:22.823
Coastly for novice. do u know about any sound cards for taking 10 inputs? – mandaliya saurin – 2015-09-16T18:35:23.133