Buying in Canada, bringing back to US

I have found scads of threads on this question but I can find no easy answer. I've looked at government website, other forums, and it's astonishingly confusing. 

I live in northern New England and Montreal is the closest city. Here's the basic question: if I drive into Canada, buy a NEW piece of stereo equipment, and drive back into the US, what will I pay in taxes, tariffs, customs, duty, whatever the fees are? (Will I pay taxes in Canada, too?) And what if I buy a USED piece of equipment? (Let's assume at least $4000 CAD.) Does it matter if the item was manufactured in the US? 

I've spent a fair amount of time looking at the US government's website. It's ... overwhelming. It looks like the "rate of duty" for loudspeakers is either free or 35% (quite a difference). There simply has to be a simple answer. 

I've crossed the border many times and I know they don't always check, etc etc. But I would declare whatever I buy. And also: I'm not talking about having something shipped. 

Thanks! I know this has been discussed out here for over a decade. But I am hoping someone can tell me in simple terms what the duty (tax, customs, tariffs) rates are for stereo equipment in 2020.

Theoretically, anything manufactured in the US or Canada should be importable duty free.  I have never tried a high dollar item, but my wife and I have traveled to Canada many times (we’re about 20 minutes away) and have never had to pay any duties on items up to a few hundred $.  

As for the Canadian sales taxes, I believe you will have to pay them, can’t speak for Quebec, but in Ontario it is 15% and cannot be refunded.  I know, I tried.  It’s possible you can work something out with the store, but typically they have to ship the item out of the country to waive sales tax.  Perhaps the store has an arrangement with a go between in the states that will lessen the pain.  

One thing to make sure of, that the manufacturer will honor the warranty if bought in Canada and taken to the States.  No idea of how each manufacturer handles this, but what I have seen is in Parts Connexion ads which state “For Sale in Canada Only”.  Buyer beware!
Thanks! I have read that anything under $200/person is duty free. Most of the information out there seems to be about alcohol/cigarettes/cars, and most of it seems directed at Canadians (I almost typed Canadiens) bring goods back to the US. 

My worry is getting to the customs/border crossing and getting walloped. 

If I buy used, then ... maybe there's no sales tax? Inquiring minds...
the import tax/brokerage level for personal imports into the USA is $800US. it used to be $200US.
beyond that number the taxes and duties begin.
My experience is that what you pay depends on the customs agent you get when you make your declaration. When I drove a used pair of made in England ProAc speakers back from Vancouver Island to Washington State the agent knew enough to investigate because the boxes said 'Manufactured in England'. I told her what I'd paid but didn't have a written receipt. She had no clue what that meant in terms of the duty. After almost half an hour looking through a book that looked like the combined phone books of all the New York boroughs she came up with a figure of $53. It was obvious she couldn't find an answer and simply settled on what felt fair to her. I paid it and drove on.
I think I looked through the same "phone book" of regulations online, the "harmonized tariff schedule." It's baroque, the whole thing. And what if she had said, "that will be $533"? It feels utterly random. I find it incredible that a simple question--"what will the duty be on a pair of used speakers?"--doesn't have a simple answer. I wouldn't want to get to the border crossing with an expensive purchase not having any idea what I was about to pay.

This thread, then, is like all the other threads on this topic out here--fairly useless. (That's on me, not on the helpful responses.) The answer is that no one knows what I would pay in duties/tariffs/etc on a pair of used speakers, perhaps not even the customs agent. 

I think I'll keep my purchases stateside.
Northman, if you buy used from a regular store you will still pay sales tax.  If you buy from a private party, then probably not.
If the gear is made in Canada, like Simaudio or Totem, there is no duty, or wasn't after the North American Free Trade Agreement was enacted. Considering the current volatility of trade and tariff agreements, though, check before you buy.
The US custom officials can ,and often do,  what they feel like .I lived 4 miles from the Canadian border  and it was a toss up
on any given day .
I Bought Paradigm Persona  ( Made in Canada) in Windsor and brought them thru with full declaration and there was no duty I believe I still paid normal sales tax ( GST)
The US custom officials can ,and often do, what they feel like .I lived 4 miles from the Canadian border and it was a toss up
on any given day .
Absolutely incorrect, custom's officials do not make up the rules, the rules are explicitly written in black and white.  In some instance, custom's officials may choose not to enforce said rules.  IME, the more expensive the item, the more strict the enforcement.  I would factor in the total cost of importation to the purchase price to allow one to make an informed choice.
Absolutely incorrect, custom's officials do not make up the rules, the rules are explicitly written in black and white.
Then help the op out and please post "said rules in black and white"
Or at least the pertinent salient points