any lawyers in this forum care to give an advice?

The lawyers are working for pay. Beware of that.

Great point. 

Seriously? Do you work for free? How about your mechanic or doctor?

Most of the advice thus far is what can be done long before you reach this stage. At this point you likely need a lawyer since no one is speaking to you, you allege there is a forged delivery signature and there is a significant about of money at risk. A  lawyer can give you state specific advice of your rights and remedies at this stage of the transaction. There are usually time limitations for your remedies and you are spending valuable time looking for a "magic bullet" on the forum. 

I am licensed in California and Massachusetts, but the advice is pretty much the same everywhere.  First, assuming that the dealer was an authorized dealer, and assuming that the dealer arranged for shipping (even if you were charged for it), the sale is not complete until it arrives into your possession in working and undamaged condition.  You have an easy claim against the dealer and I would also name the speaker manufacturer as a defendant as well, because if he is in their dealer network, they have a vested interest in replacing damaged equipment.  Easy case.  The dealer can fight it out with the freight company.

If YOU arranged for the shipping and paid for it, they can argue that the sale was complete at the delivery to your chosen freight company, and if it was damaged in transit, you have to take it up with the freight company.  The problem there is that as a common carrier, the freight company's liability is limited to something like 60 cents a pound, unless you purchased insurance to cover the value of the speakers.  Not that you can't sue them for negligence, but there is a defense.

Third, if you paid by credit card, such as AMEX, many of the cards will cover you for defective or damaged products purchased with their card, and you can make a claim to the card.  with proof, the card company will charge back the purchase price.  You can even try that if you were responsible for the shipping.  Without further information, its tough to give you any more than broad generalities on how I would handle it if it was me.  

I had purchased a sub on here and the seller had it boxed up and UPS and shipped UPS.  It arrived to me looking like it was used as a football, box broken, corners of the sub dented, knobs broken.  Seller denied responsibility.  I opened a PayPal dispute. they denied it for reasons unknown, and I immediately called them and argued with them and pointed to the pictures and unboxing video.  I was refunded my money, and I believe that the seller got the money from UPS, because their store had packed and shipped.  DO NOT BE PASSIVE.  Go after everyone to get a replacement or your money.

 As a former UPS driver, I can assure you,95% of UPS employees have no regard at all for the merchandise. ''FRAGILE'' means nothing at all.I don't think FEDEX or DHL are much different.  My advice? Stay away from mail order HI-FI equipment.

@rockysantoro 

Thank you very much for your perspective. 
 

I typically purchase through a dealer and he delivers it. If there is a problem… doesn’t matter what kind… he deals with it.

I had an expensive piece of art delivered by ups to my house when I wasn’t there and the box was damaged. I took pictures of the box the way they delivered it. They I open up the box and the frame was damaged so I took more pics of the damage. I submitted a case to ups with all the pics and I got a new $2000 frame.

on expensive purchases, I always pay for signature required so when it’s delivered, I can check the condition of the box before I sign for it and if it is damaged, I will refuse the package.

For years now, I won’t ship expensive equipment, local sale with cash