Upgrades for a cheapo tube linestage

I have a Audcom AP-110 w/remote I recently fitted with 5670's RCA's.A nice inprovement.
It came with Auricap upgrades when I bought it used.
It has plastic tube sockets in it.If I were to replace them with ceramic,would there be a audible difference?
Any other fairly easy mods to do?
Whats a good source for parts?
Hi David. I think that tube sockets may make a difference for you. I also think that improving the quality of the input/output jacks would help. Also changing any of the point to point wiring with something like Cardas wire would be good. Upgrading the volume control pots to something like the Alps units is a good mod that is pretty cheap and easy.