[1] The company launched the K250 synthesizer/sampler in 1984: while limited by today's standards and quite expensive, it was considered to be the first really successful attempt to emulate the complex sound of a grand piano.

This instrument was inspired by a bet between Ray Kurzweil and musician Stevie Wonder over whether a synthesizer could sound like a real piano.

Hal Chamberlin (mentioned below) developed software to run on Apple II class computers, which would allow extensive control of the very rich possibilities of the K150.

The K1000 and K1200 (and their rack-mounted variants) were designed to deliver the sample libraries developed originally for the K250 to a wider audience in less expensive and physically more manageable forms.

Unlike the K250, these instruments could not sample new sounds directly; but their programming architecture and operating system were evolutionary steps that would culminate in the K2xxx series.

Although initially very expensive, Kurzweil instruments were popular in top recording studios and for use with music production for film because of their high-quality sounds.

Each voice of the K2000 is able to play a separate program, allowing for smooth transitions during live performance - this simple feature took Kurzweil's competitors more than a decade to match.

Additionally one could add digital input/output (I/O) to connect S/PDIF or ADAT inputs and a program RAM (PRAM) expansion for loading larger soundsets or MIDI songs into memory.

In 2008, all K26xx series synthesizers were discontinued by Kurzweil Music Systems, although inventory still remained as of August 2008[update].

Although marketed as a new product line, the K2700 largely extends the synthesis engine and display and control layout of the Forte and PC-series performance keyboards.

It was good for this purpose because it had 88 fully weighted keys and the ability to set four zones for controlling different instruments.

In 2011, Kurzweil released the PC3K series of keyboards, which added the ability to load K2xxx-series samples and programs (with limitations).

The Kurzweil MIDIboard, a dedicated MIDI controller, was conceived of and specified by Jeff Tripp, then president of Key Concepts.

It was perhaps the first of the pure keyboard controllers, brought to market to complement Kurzweil's rack mounted synthesizers.

'MIDIboard' was, in fact, a Key Concepts trademark, transferred to Kurzweil Music Systems as part of a licensing agreement.

Released in 1988, the MIDIboard's software and electronics were designed under contract to Key Concepts by Hal Chamberlin, then of Micro Technology Unlimited.

Marketed as "the ultimate all-in-one gigmachine", the Artis is an 88 key weighted action keyboard, in a newly designed, relatively light package of 21 kg.

A newly sampled Steinway model D grand piano in six velocity layers with pedal noise effects.

Other than aforementioned splitting- and layering abilities, and effects manipulation on pre-programmed controllers the Artis has no on-board editing options.

However, a company called "Soundtower" released an editor application for Mac, PC, and iOS devices, allowing for full V.A.S.T.