Aliexpress
Click here… to search for XDUOO XD-05 DAC Headphone Amplifier on Aliexpress
Here are coupons that you can use.
Latest coupon code price check (UTC time):
Banggood
Banggood warehouse is located in China. There is one coupon available! Pretty cool, huh?
Link: Banggood product page
Coupon (223.57 USD): 7bcdf9
(CouponsFromChina.com tip: just apply this code in your cart after clicking “Proceed to checkout”. Click to copy code and open shop)
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k
Old coupons (from the oldest to the newest): elec, 2019SPEDM, AFfbG10, 502C6B, BGCITYADS2019, BGE13, BGMPB2020, BGAFF10OFF, bGhOnEy10, BGdragonBoat, BGSS10%SW, bgshOOp10, BgoFErTaSchInA10, BGELIG0920, BgcLuBofErtA10, BGCuponation10
(there’s a little possibility that old coupon will work)
Price history and price alert
Do you need price history chart (for all/most countries) for XDUOO XD-05 DAC Headphone Amplifier? There we go.
Price records source(s): Gearbest, Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).