When mentioned aimp2, to explain my problem exactly. Sounds sometimes turn louder (and stays for quite amount of tim) like when you move preamp on aimp2 eq by +2, +3.

Try using another player like foobar with Wasapi as well? Might be some funny dsp going on in the background that you don't know.

Also if its hardware and you have enough ram, try using the full file ram buffering option on foobar. Its located under
File-> Preferences-> Advanced-> Playback-> Full file buffering and set the buffer to 50000kb or something. Just so we know that its not your HDD or some lag in hardware that is the problem.

EDIT: Also look at your soundcard settings to make sure you disabled ALL enhancements. Another place to look is if you have say skype's settings or something which reduces your volume during comms.

Right click Playback devices in Windows to see your soundcard, head to the Communications tab and check that Windows is doing nothing to reduce volumes when using comms like Skype, Teamspeak etc.

It is always worth asking silly questions, of the is-it-plugged-in sort, when trouble shooting. I've wasted vast amounts of time by not looking at the simple things first.

--- check the Windows volume levels for that device. I have no idea how, but sometimes they seem to have a mind of their own. This is often the solution to no sound, rather than sound too loud. But check, anyway.

--- check the volume settings in the software. It's easy to swipe a mouse over that without noticing.

I hate Windows. I gave it up at WinXP... so I can't help further with the details.

(Linux has its little quirks for audio too. hey ho, nothing's perfect)

Yup, there is a substantial difference between saying 'need' an amp because volume is too low, and an amp that improves or hinders the SQ of the phone in question.

We were just chatting the other day in the chatbox about how loudness is portrayed in music and different frequencies, phases and time intervals, and how the ear and brain perceive those changes.  So what might sound loud enough unamped via a test tone or specific band, might not translate over to proper controlled rendering across the entire dynamic musical spectrum. 

Some things to listen for might be better transient response to dynamic swings, better blackground with cleaner/sharper imaging, more rounded/complete sense of instruments and performers filling up the soundstage (more realistic and natural rendering), more contrast in timbre between highs and lows, etc.

In most cases amping should be thought of similarly to comparing wav files to low res mp3s.  Does anyone 'need' wav files or lossless?  No.  Is it possible that they would sound better?  Yes, possibly depending on circumstances.  You are simply presenting more information that is not otherwise being lost.  Same for proper amping with a relatively transparent amp or source.  You are losing less information in your music than the headphone would being underamped.  It sounds kind of like a lower res file when a phone is underamped, except not necessarily with the grain or roughness of digital compression. 

It's an individual question for the most part.  Which means listen to your phone unamped and then amped with a clean source, and if you don't notice an improvement (for you) save your money.

Hope that helps.

Note: most if not all amps are colored to one degree or another (including the original source you are comparing with), so you could also make things worse or just different.  Based on most of the audiophile market, this is usually the case sadly.

Sooooo i think my soundcard blew last night.

After instaling wasapi, I found soundcard settings on volumes (previously I could only find speaker). So I went to enhancements, and there was only one on the list and marked "DC offset". So I clicked all enhancements disabled. And it was good for couple of minutes, then I shut down foobar and opened aimp, it was good for couple of second but sound just exploded! Crazy loudness, it was just some BRRRRRRR noise, i felt my laptop speakers wanted to explode. Shut it down, disabled in safe mode, turned on, and when enabled in normal mode this noise came again. I supose it's blew out, I don't think it's drivers. I don't know should I even try to reinstal drivers? I'm afraid that I will screw something more on my laptop if I let soundcard to work wild again.

Well, I think my money savings for monitors are going for soundcard. At least I will have a decent one.

Think I will get one of those 5, 10 euros soundcards just to do the job until I find something decent.

Also when I do troubleshot this comes out, so I think it's done.

Possible to uninstall the drivers (Right-click in Device Manager, click Uninstall, tick "Delete the driver software for this device.") and then re-install the driver, reverting the change to settings that you made?