US Customs fees. What should I expect ?

In my experience, it is completely arbitrary. I used to purchased many Burmester, Ayon and MBL preamps/dacs/amps from Europe (England / Netherlands / France / Germany). Rarely got taxed, regardless of USPS or UPS.

But for "inexpensive" stuff like Kharma low end cables, or some DIY $300 amp, USPS and UPS happily tagged on the import duties.

Funny thing is I never got taxed on stuff from Japan, Hong Kong nor Taiwan. However, 100% of the time, I got taxed on stuff from South Korea.

The rate is reasonable nevertheless, but be weary of using UPS or FedEx since they tagged on ’custom processing fee’ which is high.

I see. Do they send you a bill or you have to pay when picking up ?
I don't mind reasonable rates and smooth delivery.
I think, most likely it would be TNT or EMS.
Thinking about European integrated shipped from Europe or Asia and maybe new Nottingham tonearm from the UK. I hope I will never have to have the speakers shipped from overseas, but try to find used Kharma in North America, especially their lower models, as an example.
Well, Studer deck is a possibility too.

I have ordered 3 pieces from Yamamoto Soundcraft in Japan over the last 5 years, the first one costing $900.00 was never taxed the second costing $2800.00 was never taxed the third costing $1650.00 was taxed at what looks to be just short of 2% and was paid by then billed to me by FedEx who Yamamoto uses to ship his equipment.