Dear Ramesh,
I have bought the North Star 192 (upsampler and dac) from the Greek distributor one month ago. I am using it with my Micromega Stage 2 as a transport and have seen a big difference especially in vocals which are becoming analog like (but not quite). I am sure that if I change to a real transport I will see a big improvement also.
The comments I have seen for the model 4 (upsampler only) in Greek audio magazines mention it as a bargain. Also from what I know everyone who has heard the 192 has bought it including one selling his Meridian 563 and one his Theta Data.
My system
Michell Gyrodec/SME 309/Clearaudio GammaS
Micromega stage 2 / North Star 192
Musical Fidelity Nuvista/ Nuvista 300
Von Schweikert VR4 Gen II
Best of luck