Virtual-sound software modules require a lot of computing power (you can slow a Power Mac G5 to a crawl by using too many instruments), so if you want to replace your audio hardware with virtual-sound modules, they need to sound great.

Spectrasonics' Trilogy bass module and FXpansion's BFD drum kits are examples of sampling done right; they offer an amazing array of sound-customization tools. Both the RAM-intensive Trilogy and the CPU-hungry BFD support the Audio Units, VST, RTAS, and ReWire plug-in formats of major sequencers, as well as Propellerhead's Reason sampler-and-synth app. (Apple's Logic and MOTU's Digital Performer support Audio Units, Steinberg's Cubase supports VST, and Digidesign's Pro Tools supports RTAS.) BFD also includes a stand-alone (non-plug-in) version that can be played independently of a sequencer.

BFD

BFD's superb sound quality is complemented by its extreme flexibility. Multiple acoustic drum kits and solo drums were recorded in a variety of mike positions and velocities, and you can mix and match the resulting variables at will. You can also create your own rhythmic patterns, or use the stylistic varieties in BFD's Groove Libraries and fills as a drum machine.

BFD's clean interface makes it easy to audition, specify, and tweak sounds and to save your own handcrafted tones and sets. The program lets you preview images of its stock drum kits, from which you can visually choose and audition individual drums and cymbals. This view is useful and fun during setup but can lead to unnecessary graphics and CPU drain during recording and playback.

Trilogy

Trilogy offers 3GB of bass instrument samples with comprehensive sound and parameter controls. The package's acoustic-bass component is a jewel; it features upright bass and bass guitar, recorded via mike and/or a pickup. The electric-bass sounds include picked, slapped, and muted four-, five-, and six-string basses. The jazzy Jaco Fretless sounds wonderful. The synth tones feature a host of full-bodied analog sounds from famous vintage axes such as the Minimoog and Oberheim SEM.

There are LFO (low-frequency oscillator) filter and envelope controls for every sample in Trilogy, which help you modify the tones. Each sound file consists of two layers that can be specified and edited independently. The layers are invaluable palettes for creating masterful sounds.

The app's only weaknesses are in its installation and OS 9–only manual. To get going in OS X, register at Spectrasonics' site (www.spectrasonics.net) and download OS X CD Joiner.

Macworld's Buying Advice

The sonic quality and user controls of both BFD and Trilogy are first-rate: you get great sound and seemingly endless, yet easily accessible, editing capabilities. Trilogy's installation hassle is a one-time nuisance on the road to great music.