The Mooer solo is quite the unapologetic clone of the revered Suhr Riot, a boutique-grade distortion box known to be the go-to pedal of many professionals (including the incredible Mr. Guthrie Govan!). However, I, unfortunately, do not own a Suhr Riot in my arsenal and therefore cannot make a comparison between the clone and the original. This review shall discuss the Mooer Solo based only on the Mooer Solo.
The pedal has a very typical setting as seen on countless other distortion and overdrive units: Gain, Volume, Tone. It should be noted that this pedal is of a high-gain nature and should not be treated as one that sings the blues or does the crunchy punk tone. Although the Gain knob retains tonal integrity throughout its rotation (Low gain setting can also be nicely utilized), what fun is there if a high gain pedal's gain is not turned up? At above 12 o'clock, the pedal truly shines (particularly if given a boost in front) and delivers not only what its name "solo" suggests, but also beefy, thick rhythm tone that goes great with humbucking guitars. The sound is very organic and punchy, having just the right amount of growl and wildness for hard rock and metal rhythms.
The distortion of this pedal is rather "dark". It comes with a certain quality that heavier genres would appreciate.
As a solo tone, as its name suggests, this pedal offers generous amounts of gain (as previously noted) and consequently great sustain. String definition and clarity is maintained - the pedal hardly gets too muddy or muffled. Even distorted let-ring passages are not a challenge for this pedal.
A feature that distinguishes this pedal from other dirt boxes in the market is its three-way toggle switch which conveniently switches between three clipping modes, or simply "modes". These are normal, tight, and classic. While the "normal" setting, as its name suggests, doesn't strike remarkably, the other two are noticeably more dynamic and interesting to the ears. The "classic" mode is similar to the "normal" mode, which has a rather flat EQ and bland character, the "classic" mode offers more bite and crunch than its counterpart. It has an "open" character that is reminiscent to amp distortions of Randall and Peavey heads alike, a very promising sound to use. The "tight" mode, when engaged, is noticeably louder in volume (changing the mode withing a song would mess the balance up) and has slightly less gain. But the sacrifice of gain brings about a worthwhile twist in the pedal's tone. This mode covers very modern distortion sounds, even approaching (but not reaching) the much coveted "djent" sound used by many these days. The tone is, well, nicely captured by the name of the mode. There isn't much to describe, really.
All in all, this is a great pedal if you want a formidable heavy rhythm tone featured in heavier genres. This pedal also works if you wish to have a soaring solo tone with lots of sustain and gain.
The solo drive can be used to play lead riffs beautifully and very well. It can handle being played for a metal tone if it has to but not perfectly. The three tonality options it has (Tight, Natural and Classic) don't change the sound enough for it to be a selling point.
If you need a distortion on a budget, you can get this if you want massive power for lead riffs. But if you want something that gives you lots of versatility, rather get the Hustle Drive.