You cannot do 8 at once. Well not quite true. You can use a stereo microphone technique to mic the whole ensemble ala live performance. Otherwise, the hard and fast rule is one microphone per input channel of interface. That is why too often advice is given here at RO to buy for future needs rather than because of immediate urges.

Are you talking about my audio interface?

Yes.

That was actually a present from my uncle. D:

You know, here's the thing about presents. If you have expressed your appreciation appropriately and have given honest effort to utilize it and it still doesn't meet your needs, then you have no further obligations to continue handicapping yourself. I don't remember what interface you have because there are too many threads I answer so it's always helpful to remind folks what that interface in fact is.

Lexicon Lambda

You can do 5 inputs with that. You'll need a two channel preamp to utilize the two line inputs with microphones. The 5th input will accept a guitar or bass direct from an instrument cable. You just can't squeeze eight out of it without summing down from another mixer and that defeats the purpose of multi track recording.

Something like this? http://pro-audio.musiciansfriend.com/product/ART-PRO-MPA-II?sku=581817

Yes. At least on the MPA Gold the tubes could be changed out to better ones and it improved the whole unit.