Use escrow service to pay for speakers?

Seller on what website?

You can check the seller's feedback.

If you use PayPal you are covered as well as with many other platforms such as eBay, and Amazon.

Most credit card companies and banks also cover you.

Audiogon .

Feedback is not always a reliable resource, I've heard.

I have not registered with Paypal. In fact do virtually zero online banking.

Hoping to pay by a secure method.

I doubt individuals use cards? Will check that, thanks.

Lots of ways to pay by a secure method. Many fewer to recieve by a secure method.

With the amount of scams going on, using a more secure electronic payment system is best. At least there is some assurance you can recover your money in fraud. Cash in hand and travel is best. 

PayPal does offer some protection but it's limited to the honesty of the seller.   Google top ten PayPay scams for an eye opener.  Conversations with the seller.  Video calls to view and hear the equipment.  Asking to see the original invoices.   In the end,  if  you get a good feeling, it's still a leap of faith.  Your due diligence will usually tell you if proceeding is the right move.  Best of luck.

Sounds like you're interested in buying from an individual, so that leaves methods like credit cards out. Tough one if it's for substantial money and you can't do a person to person transaction. Sometimes it's best to err on the side of caution if it's a leap of faith you're not comfortable with. Better to lose out on an item than lose all your money.