Two of these (channels 1 and 2) feature combi XLR/TRS connectors suitable for balanced or unbalanced mic and instrument signals, while the other two (channels 3 and 4) use standard XLR sockets. The front panel is dominated by the four microphone inputs. With a footprint not much bigger than a Harry Potter novel, the Fast Track Ultra packs a lot of features into a pretty small space. So if you are in the market for a compact, multi-channel audio interface with a few bells and whistles thrown in, is the Fast Track Ultra worth a serious look? Warm-up Lap However, the feature that perhaps immediately causes the Fast Track Ultra to stand out is its onboard DSP processing. This is all housed in a compact desktop unit with USB 2.0 connectivity to the host computer. The latest addition to your dilemma is M-Audio's Fast Track Ultra, which provides six-in/six-out analogue audio interfacing with 24-bit audio at sample rates up to 96kHz, alongside stereo S/PDIF digital I/O and MIDI I/O. There is no denying that home and project studio owners have never had a better range of audio and MIDI interfaces to choose from, whatever their budget or feature requirements. The world is simply teeming with audio interfaces these days, so what does M‑Audio's latest offering, the Fast Track Ultra, have that the others don't?