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GuitarFlex vs Strum GS-2

Strum GS-2 and GuitarFlex are the closest pair on this list: both are modeled, so neither plays recordings. Strum GS-2 is Applied Acoustics Systems' guitar synthesizer: 253 guitar presets, on Windows and Mac, for $199. GuitarFlex has presets for steel-string and nylon-string acoustic and electric clean, crunch and heavy guitars, a download of 18.2 MB, and a price of $79.

What they have in common

Modeled. Neither plays recordings of a guitar.
Windows 10, 64-bit, as a standalone program and as a plugin, with no other program needed.
Acoustic and electric guitars in one instrument, steel-string and nylon-string acoustics and clean, crunch and heavy electrics.
The guitar itself to shape. Strum GS-2 lets you choose string material, bridge, body, pickup and pick or fingers. GuitarFlex has panels for the pluck, string, pickup and body.
An amp, a cabinet and reverb built in.
A way to try it first. Strum GS-2 has a fully functional 15-day trial. GuitarFlex has a demo you can download and try before you buy.

Where Strum GS-2 stands out

Mac as well as Windows, with AU and AAX plugins.
Strumming built in. It recognizes the chords you hold and places them on the fretboard with guitarist's voicings, and special keys play down and up strokes, scratches, mutes and picking patterns.
707 MIDI strumming loops, 406 acoustic and 301 electric, to drag into your host. GuitarFlex has no patterns of its own.
More presets: 103 acoustic and 150 electric.
Slides and bends from the pitch wheel or aftertouch.

Where GuitarFlex stands out

$79, against $199 for Strum GS-2.
A stated size. GuitarFlex is an 18.2 MB download that installs at 43.9 MB. AAS lists a 64.3 MB Windows installer.
No account and no online activation. A license key and your email address, entered once for each Windows user on each computer, and one license for one person, to use on all of their own computers. AAS authorizes by challenge and response, automatically when you are online, and asks for one license per computer for professional or multi-user use.
It never connects to the internet.
Four slots (A to D) to switch between sounds or layer them, with Compare, Vary and Randomize.
Your song to a file. It renders a MIDI file to FLAC, or to WAV with the included command-line renderer.
Built to play ComposerFlex's band, our songwriting program, on the same PC with no setup. With ComposerFlex it plays down and up strums, open, palm-muted or dead, with Strum spread and Strum fall.

Which to pick

On a Mac: Strum GS-2.
To turn held chords into a strummed part, or to start from ready-made strumming loops: Strum GS-2.
If you'd rather have a lower price and no online activation: GuitarFlex.
If your parts already come from ComposerFlex or from MIDI files: GuitarFlex.

Owning both

Both are modeled and run on their own, so they can share one PC. Try them with your own MIDI: AAS's trial is on applied-acoustics.com, and GuitarFlex's demo is here. This page doesn't compare how they sound. That's for your ears.

The facts side by side

Every fact about Strum GS-2 is from Applied Acoustics Systems' own pages, checked on 7 November 2026. Prices are list prices in US dollars; sales come and go.

	GuitarFlex	Strum GS-2
How it makes its sound	Modeled. It computes every note as you play, from the physics of plucked strings: the acoustic presets sound through the guitar's body, and the electric presets through a pickup, an amp and a cabinet. It plays no recordings.	Modeled: the maker's page lists "the benefits of physical modeling" and calls it a synthesizer. Its pages do not mention samples.
Price	$79, one-time	$199 for the synth only; $399 with 20 sound packs; each sound pack $39. A 30-day money-back guarantee on orders from the maker's web store
Download and disk space	18.2 MB download, 43.9 MB installed	Windows installer 64.3 MB; macOS installer 77.9 MB
Memory the maker asks for	4 GB, with 4 cores or more and 100 MB of disk (the minimum we state for every Flex program)	Less than 256 MB of RAM per instance; for standalone use, an Intel Core i5 (circa 2015) or later, or an Apple M1 or later
Runs on	Windows 10 and 11, 64-bit	Windows 10 64-bit or later; macOS 10.13 or later (Intel, or Apple M1 and later)
Forms	Standalone and VST3	Standalone, VST2, VST3, AU, AAX Native and NKS, 64-bit
Needs another program	Nothing else	Nothing else (standalone included)
Copy protection	A license key and your email address, entered once for each Windows user on each computer. No account and no online activation.	The maker's own challenge/response copy protection; installers authorize automatically when online, and offline authorization is possible
Computers per license	One license for one person, to use on all of their own computers	For personal use, every computer you own; for professional or multi-user use, one license per computer (the maker's sales FAQ)
Demo	A demo to download and try before you buy	Fully functional for 15 days
Guitars included	Presets in groups: steel-string and nylon-string acoustic, electric clean, crunch and heavy, and a two-guitar band preset; four slots to layer sounds	253 guitar presets: 103 acoustic (steel and nylon, several body shapes) and 150 electric (single-coil and humbucker, in clean, crunch and distorted settings). Chord recognition, which places the chords you play on the fretboard with guitarists' voicings (open, movable, power chord, drop); special keys for down and up strokes, scratches, mutes and picking patterns; 707 MIDI strumming loops (406 acoustic, 301 electric) to drag into your music program; slides and bends by pitch wheel or aftertouch, vibrato by mod wheel, hammer-ons and pull-offs; controls for string material, bridge, body, pickup and pick or fingers; a 2-channel amplifier, spring reverb, speaker cabinet and three effects racks

More: virtual guitars compared: modeled and sampled, a table of 25 products, and all about GuitarFlex.

If something here is out of date, write to [email protected] and we'll correct it.

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