I'm having the same issue.  It seems to be in every midrange frequency as you say that the subwoofer picks up.  They're the upper end of the frequencies the subwoofer will actually produce and so are the punchiest and cause the most rattle.  It's apparent for me when i'm listening to music the most

I just received my XPS 16 on Friday and the first thing I noticed afterr playing one the sample audio files was a very bad rattling/crackling of the speakers,. I'ts not bad at about 50% level, but higher and it is horrible. Sounds llike the speaker is cracked or something. It's fine through headphones, but I'm not sure I can keep this laptop always knowing I can't turn the volume up. Not sure about a subwoofer in this thing. Didn't know it had one. It's too bad because everything else seem to work perfectly so far. I think tomorrow I'm going to tell Dell to replace it. It will always bother me.

After looking at the speakers a little closer, now that I realized there was a little subwoofer. It appears to be at the bottom right of the touchpad, as mentioned. That is exactly where the rattling is coming from. If that was turned off, the sound from the 2 upper speakers would probably be OK. There is diffenitly a problem there. I tried to play a Brooks & Dunn song and even at 50% volume the little speaker sounded as if it was going to rattle itself apart. You can turn the SVM on in the audio control panel and this will help, but isn't that defeating the purpose of the little subwoofer. This is definetly unacceptable and must be  looked at. I will have  it replaced as I like the overall functions of this laptop and like I said before, everything else so far seems to work great. Even listing to music on the headphones is outstanding. With this fixed, I feel this could be an outstanding laptop. The size and weight to me is perfect for this type of laptop.

Tkd,

I have this computer, and use it as a desktop replacement. I use a MP3 soundock to enhance the sound.

I don't normally listen to music from the laptop speakers. I do occasionally watch a movie without the headphones. I understand what you are saying though, but I guess after spending this much money on a laptop, I want everything to work as it's suppose to. It will be interesting to see if the replacement laptop has the same problem. This rattle is not just small, it is very annoying.  They should just have left this little so called subwoofer out. Not sure what they are trying to do with it anyway. Without it, I wouldn't have any issues with this laptop from the other 2 little speakers.

Tkd,

In the US, you have 21 days from the invoice to return a product. In different parts of the world  the return period is different.  I would contact Dell about this ASAP.

Hey Tkd,
As I was saying, I had the same issue.  I resolved it by calling Dell Tech support, and informing them of the problem.  Apparently a few of the new XPS's have shipped with dead subwoofers.  It was covered by the warranty, and they dispatched a technician to my house to replace the speakers.  I recommend calling or chatting Dell to resolve this issue.

Since I just received the laptop on Friday and being stationed in Germany, I decided I would rather have it replaced than trying to get it fixed over here. I called Dell today and they are going to send me a replacement. Great customer service from Dell. I have bought quit a few computers from Dell and have always been satisfied with any problems or issues I have ever had. I really like this laptop alot and if the replacement has the same issue, I will try and pursue the technician fix. Not exactly sure about the international warranty but on my wifes XPS 17, I had it transferred, but have'nt had to try it out yet.  I might though because it is developing a nice light bleed at the bottom of the screen, about a half inch high. My wife don't care but when I look it, it bothers me.

My Studio XPS 16 has the exact same problem. I got my subwoofer replaced by a dell tech. However, the rattling still persists. Tkd, can you tell me whether your replacement fixed the problem or not? Thanks.

I got my subwoofer replaced as well, and now the rattling has started up again.  Is the little subwoofer just easy to blow? or does it not handle movement well?  this definitely needs to be looked into.