@Praba - I've built a couple of devices like this and never had any issues requiring isolation transformers (I have some but never fitted them as it worked fine as is).
@David - I used a USB cable "Mini USB 5pin male to female with screw panel mount extention cable" from ebay (mine was wired incorrectly as the colours were wrong according to the USB standard and had to wire according to how they had it set). I cut this cable to suit and hard wired it to the USB hub (removed the original connection).
My USB hub was a Startech one, but basically any similar one that you can fit inside your enclosure should work. I removed 2 of the USB sockets on the hub and hard wired my stripped down USB sound card of which I also removed the USB connector and 3.5mm audio/mic sockets and soldered it direct to the hub, plus added connector pins for the audio/mic (CD-ROM) cable. I only went to these extremes so it would all fit inside my enclosure. If your enclosure is big enough, you may be able to get away with simply plugging it all together.
The USB sound card can be found on the famous auction web site. Mine was an "External Virtual USB 3D Sound Audio Card Adaptor Converter Mic/Speaker PC Laptop"
I hard wired the Raduino USB side of the connector to the hub as well, but didn't connect the 5v power line (the Raduino is powered as normal).
To program the Raduino you have to have it powered up as normal.
I started out by proving it all worked by assembling all the component parts externally, using USB and audio/mic cables to suit.
The inspiration for the basics are here http://www.g4ilo.com/usblink.html - I just fancied it 'all-in-one' with CAT control.
I use KD8CEC's firmware http://www.hamskey.com/ and use the pre-built hex files and xloader so no need to compile yourself.
Ian's firmware allows CAT control emulation without necessarily needing any hardware mods.
I've worked all continents on my ubitx on FT8, so it does work ;-)
Not tried a pan adapter and probably won't 'hack' my ubitx any more (maybe!).