upgrading XOs - what are some good choices?

[numlog]

Im looking to upgrade the XO in the the DAC's USB controller and PC's PCIe USB 3 Card,

 

I cant get any  info from markings of the current XOs except frequency so the USB card will be first since it likely uses the cheapest possible parts, also serves as practice for the DAC as its much cheaper to replace in case something goes wrong.

Could anyone help with choosing a good XO for an upgrade?

 

Is frequency the only spec that must match the original? any recommended series to check out?

 

I'd like to spend around $20 but might go higher