Question about replacing 12AU7 tubes.


I am new to tube amps and have a question about the 12AU7 tubes in my Dared VP-300b Quasi Monoblocks. Each of them has a 300b tube and 2 12AU7 tubes.
I would like to have a replacement at hand if a 12AU7 tube goes out (also read somewhere the stock tubes are not that great).
Do I need to get matched pair or even 4 matched tubes?
If matched pairs would I put one matched pair in one mono block and the other pair in the other, or would I put one of each pair in each mono block so they have the"same" kind of tube combo?

Any suggestions about this and any tube suggestions would be appreciated?

Thanks.
utah_dude
Anybody got an idea for a supposed up-grade for a 6z4 recitifier power supply tube?
Both the driver and input tube will have a noticeable influence upon the sound of the amps. I could not find any info on the net in regards to which is which. Does your manual say anything about them? I'm sure Dared could tell you if you have an e-mail for them. Have fun!
I disagree with Bigshutterbug. I have large stock of 12AU7s; new and vintage. Telefunken are my favorite vintage tubes. Among new tubes the EH 12AU7s are very nice, but the Psvane 12AU7s are fantastic. I'm starting to lean more toward Psvane even over the Telefunkens. Warning, the Psvanes take about 100 hrs to reach their ultimate quality. First few hours they sound a little on the soft side and they were not competitive with the Telefunkens.
My experience with 12au7's is as follows- Mullard is my favorite, followed by RCA clear tops. When you factor in price, the RCA clear top is a bargain.