The choice of the soundcard (or audio interface) depends on many factors, among which recording quality, number of inputs, MIDI I/O, mic/guitar inputs (XLR etc.), external vs internal, and of course price.
n-Track is compatible with any soundcard that has standard WaveRT, WDM, MME or Asio drivers, including USB, Firewire (IEEE 1394) and PCI audio devices. Follows a list of a few soundcards that have proven to work well with n-Track Studio. New audio devices are released all the time and others quickly go out of production so the list below may sometimes report devices that are no longer in production.
Yes, n-Track takes advantage of quad core and dual core CPUs. The gain from switching from 2 to 4 cores depends on both the structure of the song(s) and the audio buffering used.
The more channels (i.e. tracks, groups, auxs) and/or effects per channel you have, the more n-Track will be able to split the work among the available cores.
Buffering comes into play because the less buffering you have the smaller must be the chunk of work that n-Track assigns to each core, so as buffering decreases the efficiency of splitting the work decreases too and you reach a point where it's faster to just use a single core. It's kind of like dividing work between people: if you have many dishes to wash you finish quicker if you many people and assign to each a portion of the available work. But if you put 4 people to wash 1 single dish you're likely to be slower than one lone washer.
Again depending on the song and CPU type (speed, number of cores, cache, shared vs non-shared cache) the point where single core may perform better than multiple cores may be from 64 to 256 samples per buffer. You can test this by toggling the 'Multithreaded audio processing' box in Preferences/Options and then performing mixdowns of a test song and measuring the time each mixdown takes for decreasing buffering settings.
Follows results mixing down a benchmark song on various systems.
The benchmark song consists of the Sometimes n-Track sample song (that can be download from the download page), with an instance of the n-Track Reverb (with default preset) on each track (instead of on just a couple of tracks in the original song) to make the song more CPU heavy.
The speedup from using two cores instead of one decreases as the buffer size decreases, but it remains positive even for very low buffering. Adding a 2nd reverb for each track yields for 64 samples buffering 1:12 vs 1:30, i.e. 20% speedup, which means that increasing the song CPU load the relative advantage of using multiple CPU cores increases even for very small buffering.
n-Track Software