FOUND: 12au7 valves matched pair

[RankStranger]

Item: 12au7 matched pair
Price Range: $30ish
Item Condition: New to well-used, as long as they have some life left in them. 
Extra Info: I have a new hybrid headphone amp (xduoo TA-20) which came with some stock cheapies and I’d like to experiment to see what, if any, difference different valves will make