DSP-Quattro ($129) reaches beyond the boundaries of traditional audio-editing software. In addition to the typical sample-editing tools, it features multitrack recording, simultaneous playback of multiple audio files, real-time hosting of virtual instruments, and real-time effects processing of audio input. Its fully configurable signal path allows you to mix any combination of audio sources, apply separate insert effects to each source, apply master effects to the mixed output, and record the results to a new audio file. Along with all this flexibility, you get a full-featured sample editor.
DSP-Quattro offers a full-featured sample editor (top), convenient marker, region, and loop management (bottom right); support for Playlists and CD burning (bottom left); and real-time hosting of virtual instruments (bottom-left insert).
DSP-Quattro can edit files in AIFF, WAV, and Sound Designer II formats at any sampling and bit rate. It can also import any file for which there is a QuickTime translator, which includes MP3 and AAC compressed files as well as audio-CD tracks. For audio files that for some reason don't load or import using those alternatives, there is a Raw Data import option that will try to translate any file into audio based on parameters (bit size and order, sampling rate, and so on) that you choose. You can simultaneously open multiple audio files for editing, and DSP-Quattro will maintain a separate, complete undo/redo history for each one, in effect making all editing nondestructive.
As with most sample editors, you can set regions, markers, and loops; you can copy and paste between files or within the same file; and you can apply standard DSP processes like gain change, reversing, trimming, removing DC offset, fading, pitch or time shifting, and so on, to any portion of the audio file. Furthermore, you can instantly apply any of DSP-Quattro's plug-in effects as well as any VST or AU plug-in effect that you have installed. Built-in plug-ins include a chorus, delays, reverbs, and various filters.
DSP-Quattro has the full spate of looping features. You can set loop points manually or by designating a tempo, length (for example, four bars at 120 bpm), and starting position. A sample-accurate loop editor allows you to match loop start and end points precisely, and a handy X-Fade Loop feature will place a copy of the looped region after the original and create a crossfade between them. By copying a loop into a new audio file and repeating the X-Fade Loop feature you can create one long audio file with as many perfectly crossfaded copies of the loop as desired.
Plug In and Play Along
In addition to instant offline processing of a single DSP effect, you can insert plug-in effects after each audio generator (audio file, audio input, software instrument, Playlist track, and so on). There are four insert slots per audio generator and four more insert slots for the Master output. In case the audio generator is an audio file, the insert effects can be printed to the same or a new file, with or without the Master effects. For other audio generators, you can record the result of effects processing by using the MasterOut recorder.
Playlists are fully implemented in DSP-Quattro, including the ability to assign different plug-in effects to each Playlist track. You can add tracks to the Playlist either from audio files on your hard drive or from audio files already open for editing. In the latter case, the track can be any region, loop, or selection within the audio file. You can set nondestructive gain change, pause time, and crossfades between Playlist tracks. Once set up, your Playlist can be exported as an audio file, exported as an audio-CD image in Roxio Toast format, or burned directly to an audio CD in Redbook format (OS X only). You can also simply use the Playlist as an audio-file sequencer, with which to play along.
DSP-Quattro can interact with hardware or software samplers in three ways: by exporting and importing audio files, by using the MIDI Sample Dump Standard (SDS), and by using the SCSI protocol. A variety of sampler-specific formats for popular models from Roland, Akai, E-mu, Kurzweil, and Yamaha are supported.
DSP-Quattro is an absolutely outstanding piece of software and an incredible value. It offers features and performance on par with or exceeding sample-editing software costing four or five times as much. The documentation is complete and accurate. The user interface is well thought out, and key commands are provided for the most often used operations. Any one of its five basic functions — sample editor, soft-synth rack, real-time effects box, mastering tool, or audio-CD burner — is easily worth the $129 price tag.