Shipping Speakers to China - Which Shipper?

I'm shipping a pair of high-end speakers (German Physicks HRS-120) to Shanghai, China. Does anyone have a recommendation on which shipper to use in terms of cost and reliability? The speakers weight about 65lb each, but have a single box, so total weight with the box is about 140lb. Hence, I don't think they can ship USPS because of the weight.

Thanks in advance for any recommendations.