Carl Martin's first attempt at a non-programmable multi-FX was impressive because of its organic analogue tone.
However, the first version of the Quattro featured a more niche vibrato effect where a mainstream modulation effect such as a chorus might have been a better option. Happily, the MkII model arrives with compression, overdrive, delay and chorus onboard.
The compression circuit has been tweaked to make it less ‘invisible’, but aside from that there are few changes.
The Quattro is housed in a rugged all-in-one metal unit with integral mains adaptor and trailing lead, idiot-proof controls, a tap-tempo switch for the delay and choice of two gain levels for the overdrive.
Along with the single instrument input we get stereo/mono outputs plus a handy FX loop (placed after overdrive but before chorus) to add in one or more additional, primarily drive-based effect.
Not only are the individual effects high quality, they create - in combination - a wonderful organic tone that's noticeably different from many modern multi-FX units. The chorus widens the appeal while the dual overdrives can be used for differing textures and/or gains for rhythm/lead tones.