When considering a soundcard for recording audio into your computer it is a good idea to look for a preamp which will suit your recording needs. The following is a quick introduction into the types of preamps available:
A microphone preamp is a device which boost the level of a microphone. A microphone is a device which converts audio energy into voltage but the voltage is very low when compared to line level voltage such as the signal from a cd player. As such it is necessary to boost a mic level signal so that a strong clear audio signal can be recorded.
An instrument preamp is used to take high impedance instrument signal and convert it into a low impedance line level signal which can be recorded. If using a device with an instrument preamp you can plug your guitar directly into the audio interface rather than having to go into an amplifier first.
A turntable which plays vinyl will output a phono level signal. Usually these are connected to a DJ Mixer which will boost the signal to line level which can be recorded. However if you are not a DJ and you just want to connect your HiFi turntable directly to your soundcard then you will need a phono preamp. There are only a handful of soundcards which offer this functionality and if you do require this type of preamp it may be worth investing in a standalone phono preamp and choose a soundcard based on other needs.
Do you need the phantom power?
If you plan to use a Condenser microphone then you will need to ensure the microphone preamp you are using is capable of providing phantom power. A condenser microphone will not produce a signal unless it is being powered by phantom power.