According review from gsmarena,and Engadget : iPhone 4 s and 4 the sound quality above Iphone 5
Please note : the stereo cross talk IPhone 5 = - 76,5 < from iPhone 4 S = - 93 < iPhone 4 = 89,6
Base on this review from gsmarena and engadget can not be iPhone 5 better than Iphone 4 S and iPhone 4.
http://www.gsmarena.com/apple_iphone_5-review-822.php
http://www.engadget.com/2012/10/02/iphone-vs-rivals-audio-tests/
Copy from gsmarena :
Test Frequency response Noise level Dynamic range THD IMD + Noise Stereo crosstalk
Apple iPhone 5 +0.06, -0.51. -91.3 91.3 0.0015 0.0093 -76.5
Apple iPhone 5 (headphones attached) +0.00, -0.26 -90.6 90.6 0.0035 0.111 -56.2
Apple iPhone 4S +0.02, -0.11 -91.2 91.2 0.0020 0.012 -93.0
Apple iPhone 4S (headphones attached). +0.05, -0.10 -91.3 91.3 0.0068 0.071 -66.7
Apple iPhone 4 +0.01, -0.07 -90.1 90.0 0.0068 0.012 -89.6
Apple iPhone 4 (headphones attached) +0.01, -0.07 -90.4 90.4 0.0036 0.092 -68.4
I believe the review from gsmarena , all my Iphone 3 GS , i4 and 4 S I bought after I read the review
From gsmarena.
This is my personal opinion base in two review above , until now I hold to buy Iphone 5
I am as funboy from iPhone this time is disappointed with the new Iphone 5
Mostly I use my iPhone as DAP and until today my Iphone 4 S is the best DAP