Originally a keyboard player in his off-time and guitar player from age 21, Scholz built a recording studio for himself in the basement of the rented apartment building where he lived, utilizing many home-built devices including a 4-track recorder and mixer.

Demo recordings made in his home studio years later became the debut album of the band Boston and proceeds of his success were used to found a company to further develop and market versions of his inventions.

The "Boston Tone" was the result of Scholz's endless experimentation with guitar amplifiers, microphones, equalizers, and other gear.

Modified equipment, which was the result of much of this experimentation, inspired some one-of-a-kind products that Scholz felt other guitarists would find useful.

Later on, SR&D added other signal processing equipment to their product line, notably the Rockmodules, which were professional half-rack effects that modularized individual circuits of the original Rockman.

The Rockman line, which was engineered using analog circuit designs, was perceived as less innovative during the digital effects boom of the early 1990s, eventually putting the company out of business.

In 1995, Scholz sold the Rockman line to Dunlop Manufacturing, Inc. which closed SR&D's offices in Massachusetts.

Today, many SR&D products have become highly valued collectibles as evidenced by listings on eBay and Reverb.

This model has an extra switch on the back to adapt the Power Soak to solid-state amplifiers.

The Rockman brand was introduced with SR&D's eponymous battery powered headphone amplifier claiming to replace $10,000 of studio gear.

The first generation Rockman combined multiple effects with high quality components and construction in a hip-worn enclosure using a built-in attached belt clip.

Released in 1982, the original Rockman (Model I) advertised "custom EQ, heavy sustain, clean/distortion control, 'chamber echo', stereo chorus" and "folding headphones".

Featuring a built-in compressor, the Rockman offered two clean modes that utilized different equalization settings with "hi power sustain": "CLN 1" can be used for R&B and country, while "CLN 2" is recommended for a wider range of use, including acoustic guitar, vocals and keyboards (electric piano, organ and synthesizer).

Rockman Model II appeared in early 1984 and advertised "quieter, cleaner, better response in distortion, and a brand new EDGE sound".

The X100 is very similar to the original Rockman in its feature set, but uses a LED-based "hard clipping" stage[3] in the distortion circuitry.

The Ace family is a much simpler Rockman design that does not have effects and uses a single 9-volt battery or power supply.

The Bass Ace has the most spartan controls, including mid and treble boost buttons.

There are roughly three categories of Rockmodules, the amplifier simulators, the sound processors and the control devices.

Compared to the Sustainor, the Distortion Generator lacks the noise gate and external loop, but includes a three-band pre-distortion EQ.

The sound processors include the EQ, Compressor, Smart Gate, Chorus, Echo and Stereo Chorus/Delay.

Its intended place in a Rockmodule lineup is after the Sustainor or Distortion Generator, but before the chorus and echo effects.

Increasing the delay time and adding feedback provides standard echo effects.

It is a dedicated analog chorus and adds foot-switchable controls for long-chorus and sweep stop.

Since many of the Rockman products include a compressor (Headphone amps, Sustainor, Distortion Generator, XP Series, Acoustic Guitar Pedal and Ultimatum based products), this effect is primarily intended to add compression when it is not provided by other equipment in the signal chain.

The Dual Remote Loop is used to interface effects and amplifiers that can't controlled by other means.

The XP series started in 1989 as a rack-mounted programmable preamplifier called the XPR that was intended for direct connection to a full-range PA system.

Due to the small production numbers, the XPRa, XP100a, XP212 and Superhead are extremely difficult to find in the aftermarket.

A second clipping stage simulates the saturation of a power section in an overdriven tube amplifier.

The last SR&D brochure featured a Rockman Stereo Chorus pedal in the same style as the AGP and the Ultimatum.

[4][5] Although it was marketed as a portable headphone amplifier, the Rockman also allowed the guitarist to plug directly into the mixer on the stage or in the studio.