i'm going to be purchasing the nt2-a studio condenser microphone but i'm under the impression i will be needing to buy an interface, could which interface i get affect audio quality etc, i will only ever be using one microphone at a time.
Which interface should i get and what should i know as i've only worked with usb microphones before?
Do i need to buy a phantom power also?
Do i need to spend 100 odd on an interface or will this work http://www.ebay.co.uk/itm/XLR-to-USB-Interface-convertor-with-48v-Preamp-phantom-power-/16 1105081721?pt=UK_Musical_Instruments_Preamps&hash=item25829c7579
What is my cheapest option?
I must confess that I'm slightly at a loss to understand why you want to purchase one of the quietest condensor mics around and then feed it into a piece of junk like that ebay item. The mic will considerably out-perform it. Yes, you need phantom power for this mic, but if you want to use it to anything like its capability, then you'll need rather more than the cheapest usb interface for it.
You'd be better served by the (cheaper) Behringer Xenyx 302 USB Mixer and interface, or for not much more, the ART USBMix 3 Channel Mixer w/ USB Audio & Phantom Power. Even though I'm personally not a huge fan of Behringer, either of these will do a better job, because the preamps in them aren't anywhere near as compromised. At this price level though, (only 16-bit A-D) you still won't be able to get the full benefit from it. To do that, you're going to need a more expensive system with a better converter.