I had both for awhile and played lots of module war
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Angel: tight, clear, & articulate. A better "quality" clear tone. It does not have the most powerful low end- but that comes with the territory of being super tight. The Balls feature improves this area, but I oddly used it more often without...when recording, typically super low end is reduced, and this mod sounds great in a mix as is.
The Powerful Low end in the Mamba is one of a kind, so understand the Angel is not on this level in this department. It does give you crystal clear lead tones with shimmering sweep arpeggios that are beautiful- especially with the mid edge engaged.
There are some similarities in the S1S0 and the Mamba. The S1S0 is not a pure quality tone mod. It has a bit of smear to it (which i like); strong low end. The sweep when set higher can get real close to a west coast friendlier-metal Salvado SLO tone- it gets more articulate and close to Angel tight. Set to the prescribed mark you get 5150 mids & power. Depending on the guitar, song style, and whatnot, I'm always flipping around the I II Fire and sweep.
The Mamba sounds like mega Recto, the S1S0 a mega Marshall. The Angel has the mid cut/boost that can kind of hint at either. The Angel cut is a cool tone, but for that sound I choose Mamba every time. The Angel mid boost can sound like a meaner more gained up and articulate SLO.
Angel likes awesome technique, speed picking, detuning, and music a bit meaner than SLO
The S1S0 is bit more forgiving for my inconsistant technique-besides sloppyness, i tend to play really hard- my tech said i play like King Kong, lol; this makes the S1S0 perfect for smoothing out my pick attack (softer/normal speed pickers may enjoy the Angel). S1S0 is my go to Lead module for any guitar/any tuning, gets used on spots where I previously used my Marshall 800 tones, has an excellent dirty crunch tone.
I just sold off my Angel (my 2nd Angel) and kept the S1S0. I know a few others around here-one rhymes with CatRig-who dumped the S1S0 almost immediatley....YMMV