I owned the original S4s for several years, mainly for gym or commuting use. It had a lot of bass, a large soundstage, and was not harsh on treble. It was perfect for the gym being light-weight, easy to fit, but the cord was annoying, slipping off often. You may find the cord cheap even for every day use.
So when the left ear went out, I decided to go for the Reference S4.
The Reference is a lot brighter sounding, fatiguing, and I had to ultimately go with the phonak PFE 012. It did have a nice bass too, punchier than the S4.
I feel the overall sound got tuned to a V shape, where the originals lacked in treble, better for my needs. If you have a lot of electronic, stay away from the Reference as you will experience fatigue.
It may be that the Reference is not quite "burned in" as I had so much time on the S4, but I don't think so.
Check out the PFE 012 as it's a huge step up. It will run you $99-125 but it's WELL worth the extra money. And it is NOT shy on bass.
Thanks, Main
Are these them?
http://www.amazon.com/Aud%C3%A9o-Perfect-Bass-Earphones-Black/dp/B003V9QDXK/ref=sr_1_1?ie=UTF8&qid=1335918086&sr=8-1
bob