The XTone is arriving next week, so I’ll know more once I get it setup. I can imagine it’s a one vst plugin per use with the pedal. So I would have Mercuriall Spark open on my MacBook and then use the XTone to switch between presets in that plugin. This is fine to me, and if I want to use a larger vst program with multiple amps, then there’s lots out there like S-Gear, Bias, EZMix. From what I’ve read the latency is said to be non-existent, the audio interface is said to be first rate. I too preferred the Mercuriall Spark to any Marshall modeller I’ve tried. This even included 2 actual Marshall amps I recorded (JVM direct out, and DSL mic’d). The Spark is that good IMO.