If you’re looking for a dedicated tone generator with the feature list of a basic workstation, the Yamaha QY-70 and QY-100 (even though a bit dated) are still IMO the best in this area. Why Yamaha discontinued them is a mystery because both the QY-70 and QY-100 were very popular and big sellers.

As mentioned if you have an iPad (or even an iPhone) that’s another option. A great app IMO is SampleTank for iOS. You’ve got GarageBand, but IMO, the QY-100’s XG sound set is better. Some of theincluded sounds with GarageBand (iOS) are ok, but some are really poor. I’ve got SampleTank on my iPhone and love it.

Sqk
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GEAR: Yamaha MOXF-6, Casio MZX-500, Roland Juno-Di, M-Audio Venom, Roland RS-70, Yamaha PSR S700, M-Audio Axiom Pro-61 (Midi Controller). SOFTWARE: Mixcraft-7, PowerTracks Pro Audio 2013, Beat Thang Virtual, Dimension Le.