I suggest you to use the stock earbuds. Everything else will sound like real crap, even if it's high end or not. I've tried almost 100 headphones with my SGSII (some of them very expensive, in the USD1000+ range) and all sound like a nightmare.

You can try the Cyanogenmod 7 nightly 81 or 82 (it's going to be released in one hour or two) and the PowerAmp Pro player (paid version). Don't expect any decent sound quality like the iPhone 4, though.

Also, don't even consider using a portable amp with, it will only make things worse, due to the terrible headphone line out and because there is no real line out dock like in Sony, Sansa or Apple products.

IMHO, you should have kept the 3GS. Everyday I regret buying this cell phone, because my intention was to use it mainly as a DAP, but it's a shame that Samsung now prefers to focus in things such as shiny borders and copying Apple products, instead of making real good cell phone like used to do two years ago.

Edit: you could try foam tips with the stock earbuds or buying cheap Sony earplugs or similar.

You should try it with Cyanogenmod, it improves the android experience a lot.

Output impedence of the SGS2 is just too high for any IEM to sound good.  its a hardware design failure that cannot be overcome with any software tweaks. Sorry, samsung fubared that part of the phone.

SLARe I'd just like to say that this phone is one of the best on the market. Perhaps it doesn't lend itself to high quality audio, but in no way have samsung stopped making high end phones.

If it is feasible I would recommend getting an appropriately sized iPod to work along side your phone. That way you can have a larger sized portable library (if needed) with high(er) quality audio and nearly everything on the market is compatible with it. I don't like to say apple products are great as I don't like the closed nature of apple's software but in the DAP market they are definitely at the top end. Especially in terms of size, UI and cost.

I've also got the SGS2.

Supports every format under the sun, moon and other stars etc BUT we do have a hardware limitation.

Its my last resort rig as lets be honest, the sound is a bit on the rubbish side lol. Why couldnt they stay with the audio hardware of the galaxy I esp now since being more "community friendly"?

I use PowerAmp Pro, and the EQ function. My galaxy's gone off for and insurance repair. 

PLEASE NOTE: The update to android 2.3.5 is said to improve the sound quality. I have applied this (and my phone generally performs better) but I have not tested this.

Maybe they wrote better code to make it work better? I dont know but many reports of this on Xda developers (Probably the best place to read up about a custom rom). If you want the link to the ROM I use, PM me. 

When I get it back from Vodafone (and their useless insurance policy hopefully on Mon/Tues) I can test the difference between SGS2 ->IEM VS SGS2 + Fiio E7->IEM.

Okay, Ive finished a bit of listening.

45 mins, 3 tracks.

I used: Samsung Galaxy S2, Phonak Audeo PFE122 and Sennheiser IE7's

I also tried: SGS2 -> FiiO E7 -> PFE122/IE7's

NOTE: My interconnect from SGS2 -> E7 was a 3.5 jack to jack using a single strand of 0.6mm 5N purity silver (3 solid strands, one for L, R and ground) soldered using Cardas Quad Eutectic Solder to 2 ViaBlue T6 3.5mm jacks on both ends. All in a sexy yellow cable sleeve with yellow heatshrink ;) Its sexy so i'll add a pic hehe.

Track 1: Inna - Amazing

http://www.youtube.com/watch?v=q3NwJF28wjU&ob=av2e

Track 2: The Roots - How I Got Over (Live) NOTE: From The Album Late Night With The Roots

http://www.youtube.com/watch?v=lf2lmZgPz-Y

Track 3: Ludacris - I Do It For Hip Hop  Last of a Dying Breed (Live) NOTE: From The Album Late Night With The Roots

Link for The Roots Album/Songs - See bottom of the page - http://www.refinedhype.com/hyped/entry/late-night-w-the-roots-mixtape-download/

EDIT: Added youtube links for these songs. Also they were ALL 320Kbps MP3 rips. I would use my FLAC library but my girlfriend has taken my 1TB HDD so I havent got much choice since I moved my library to external HDD.

Quote:

Originally Posted by Bojamijams 

Output impedence of the SGS2 is just too high for any IEM to sound good.  its a hardware design failure that cannot be overcome with any software tweaks. Sorry, samsung fubared that part of the phone.

I will edit this post with what I found of my listening time, BUT I hate to spoil it before I start (But we knew this already really), Bojamijams hit the nail on the head.

It drove my IE7's (without amp) to average sound quality - I could tell these are nice musical earphones but the loudness was missing completely. (YES REALLY, Full blast and i didnt think for a second that:  wait.... these are becoming a bit too loud). I know quite a statement since IE7's are fairly easy to drive.

I USED STOCK MP3 Player, NO EQ

MY REVIEW:

Track 1: Inna - Amazing:

Sennheiser IE7: Wide soundstage, but a thin sound. Lows are OK, highs are average.

USING THE 5.1 Sound proccessing function - Hopeless. Muddy, too bassy. Dont ever use it. lol

PFE 122: Good soundstage but slightly 2D. Flat, thin, lifeless sound. highs and clarity are very good but sounds like a cheap MP3 player with bundled earphones. Lifeless, not musical.

USING 5.1 amp/boost option - Muddy across the entire spectrum, busy sound.., no definition AGAIN. Artificial bass boost sounds like its tearing large woofers. Kind of like a 16 Year old who bought his first 10 inch sub from halfords and is wearing it in on full blast (Sounds like sh%^$%^$t! lol)

Track 2: The Roots - How I Got Over (Live) NOTE: From The Album Late Night With The Roots

http://www.youtube.com/watch?v=lf2lmZgPz-Y

IE7: Good imaging, very wide sounstage. Very musical sound but finer details and highs are reccessed. These can be EQ'd using powerAmp.

PFE122: Nice highs, great clarity but no weight to the music. Soundstage is good and quite wide. Also has a surprisingly 3D sound but lacks weight and punch. Cymbals sound good and crisp. Listen to this on full volume to be enjoyable and energetic sound.

NOTE: I stopped using the 5.1 upscale as its useless

Track 3: Ludacris - I Do It For Hip Hop  Last of a Dying Breed (Live) NOTE: From The Album Late Night With The Roots

Link for The Roots Album/Songs - See bottom of the page - http://www.refinedhype.com/hyped/entry/late-night-w-the-roots-mixtape-download/ - STREAM THE TRACK

IE7: Full engaging sound. The lower mids are a bit muddy and abit too much going on at times. Full volume is not enough to stay loud. EQ a bit of highs and it sounds more forward and agressive but without EQ - sounds good but largely due to phones used.

SENNHEISER IE7 USING FiiO E7: Separation is MUCH better, highs are well defined especially the cymbals. Cymbals have great definition to them. You can imagine ?UestLove smashing them and see the cymbals crashing and rattling. VERY VERY GOOD WITH E7.

PFE122 With Stock Tips: Only good at max volume, SGS2 amp is not powerful enough to drive these adequately, good sound but need an amp to replace or find the weight in music.

PFE122 WITH COMPLY TIPS , NO E7: better weight with comply's but highs are better without them. They are a bit too tamed/reccessed with comply's

PFE122 With STOCK tips and FiiO E7: some warmth restored. Musicality is added particularly in the mids. Sweet mids now, weight and scale is added too the Low mids and low end. Definite improvement.

SUMMARY:

SGS2 has not got the power to drive headphones to their best even with headphones that dont really need an amp to do well and enjoy your music.

IE7's musical nature helps SGS2 and with an amplifier i'd say YES, great sounding setup. SGS2 + FiiO E7 is worth it! But for the more analytical headphone e.g. PFE122's you need an AMP/EQ a lot or you're losing out on enjoying the phones as they are no where near as good as they should be.

I read incidental reports that the sound quality was inferior to the original Galaxy S. I had no idea that this was the understatement of the century.

My experience is isolated to my old Epic 4g with a voodoo sound kernel (ACS Frozen Rom 1.2 + genocide 2.0 Kernel), using my Ultimate Ears Triple Fi 10 pros.... and then using my Epic touch  4g.... well.. there is less bass... and if you eq  a boost.. the bass is distorted... but I can live with that... but I can't live with the lack of clarity.

The S2 with UETF10P (400 dollar retail/200amazon) sounds no better if not worse than my original Galaxy S with the included stock ear buds. 

Seriously WTF!!!

Either way.. there are no best iems for the S2... I'm seriously considering pulling my old bluetooth motorola S9 hds... i wouldn't be surprised if they sound better.

Good luck... btw there is some discussion that that using neutron player can by some unknown to me settings gain tolerable sound quality out of the S2... I'm thinking the water is placebo flavored for those people... but I still want to drink it.

Galaxy SII needs an amp to get full potential. I don't know if it is just me, but Android 2.3.5 on SGSII has alot better clarity than 2.3.3 and 2.3.4. I also have Galaxy S with voodoo, cowon J3 and iPhone 4S. All of these definitely sound better than Galaxy SII.