Much as I love the qin zither, I still need to rehabilitate myself for daring to query its dominance in Chinese music studies—as I observed here, it is as if the whole varied spectrum of European musics were represented mainly by the clavichord (see also here).
So here’s a rare version of the qin solo piece “No ulterior motives regarding seabirds” (Oulu wangji 鷗鷺忘機: I might suggest “Seabirds: forgetting ulterior motives”) as a duet with fiddle, recorded in 1962 by the great Zha Fuxi (1895–1976) on qin with Jiang Fengzhi (1908–86) on erhu:
In the 1954 image here, left to right are: Wu Jinglue, Wu Zhenping, Zha Fuxi, Jiang Fengzhi (looking remarkably like Yang Yinliu!), Guan Pinghu.
The qin has such an intimate solo timbre that the only other instrument usually deemed suitable to play with it is the mellifluous end-blown flute xiao; the erhu, with its modern romantic conservatoire repertoire, is generally considered quite remote from the meditative ethos of the qin. But this version of Oulu wangji shows how a simpler, restrained, selfless style of fiddle playing can blend well, enhanced by the low tuning—a model for Bach on the erhu?! It’s also effective because whereas in most qin–xiao duets both instruments play throughout, here the erhu takes the main melody while Zha Fuxi accompanies selectively with pivotal notes, almost like a continuo player.
It’s all the more poignant when we think of the date of recording—during the interlude between the traumas of the Great Leap Backward and the Four Cleanups. It may seem hard to imagine how anyone can be nostalgic for the period before the Cultural Revolution—but despite their tribulations, the stellar gatherings of qin masters, and the brilliant scholars of the era, have a numinous allure.
Oulu wangji is a favourite of qin players—among many versions online are performances by Guan Pinghu and Wu Zhaoji. As ever, John Thompson’s website is a treasury of information—for Zha Fuxi, see here, and for a typically erudite discussion of the piece, here.
The story goes back to the ancient Daoist sage Liezi: 
There was a man living by the sea-shore who loved seabirds. Every morning he went down to the sea to roam with the seabirds, and more birds came to him than you could count in hundreds.
His father said to him: “I hear the seabirds all come roaming with you. Bring me some to play with.”
Next day, when he went down to the sea, the seabirds danced above him and would not come down.
Therefore it is said: “The utmost in speech is to be rid of speech, the utmost doing is Doing Nothing.” What common knowledge knows is shallow.
 Liezi, BTW, deserves a bit of an image-rebrand to boost his ratings alongside Laozi and Zhuangzi! By the Tang his work was honored with the fine title True Classic of Simplicity and Vacuity (沖虛真經)—an award now reserved for TV reality shows.