Ok, thank you for your input :)
I thought iPhone was stacked stock with aptX though? My in-car system does have it and my i5 works flawlessly with really loud sound, no distorsion and big bass too. The iPhone itself does transmit the signal well, it might be the receiver here that needs to be aptX-able IMO.
BTW I've seen an interesting thread on xda forums today about the G2, while I was looking for almost all the "top end almost audiophile" smartphones (did take me lot of time haha).
About the mod available on xda, users are amazed by how it improves a lot SQ for both headphone jack and speaker (your volume level goes from 80% stock to 40-50%), plus it brings better soundstage, clearer sound signature. The maker of this mod does actually have an iPhone 4S so he tested them both. It is compatible with Viper, but "loudness" feature must be turned Off in Viper (you might know better than me what this is about).
About other smartphones, unless you absolutely want 4G, you will be interested by the Vivo Xplay (or just wait for Vivo Xplay 3S, it will include 4G and so much more), Oppo N1 and Meizu MX3. The Vivo Xplay 3S might also have a brother to stack against the Oppo N1, so smaller than the 3S but with a better camera and I hope the same CS and OPA audio chips.
I was tickled a lot by the Vivo haha, but I don't know if I will have the patience to wait until December or January to see what comes out.
Edited by Vanarian - 11/13/13 at 1:44pm