I recently learned about this brand of guqin silk strings: WuSheng 吳聲絲絃
The stock of WuSheng silk strings may be running very low at this Taobao shop. This is just for your future considerations.
(No I have no intentions to buy them yet. haha)
Here are three very beautiful sound samples of guqin performance with WuSheng silk strings, by guqin master Mr. Wong Chun-Fung. Enjoy! (anyone who can play so beautifully must surely be a guqin maestro!)