Amps and soundcards to play estim files

RME Babyface Pro FS

A 118 dBA line-output dynamic range, more than 110 dB of channel separation, SteadyClock FS and TotalMix FX put this firmly at the serious-control-room end of audio-stim playback. Adult e-stim users can build a dedicated stereo route to a compatible power box, keep monitoring separate and switch the balanced XLR output between +19 and +4 dBu when a lower level is needed. Machined from aluminum and bus-powered, it is compact, clinical and gloriously overqualified for making intricate WAV files behave themselves.

Focusrite Scarlett 4i4 4th Generation

Four line outputs, separate mixes for the headphones and line outputs, 24-bit/192 kHz operation and a 130 dB A-weighted D/A dynamic range make this a deliciously sensible center for computer-driven e-stim. Adult audio-stim users can reserve outputs 3 and 4 for a compatible power box while ordinary monitoring stays elsewhere, keeping system audio and deliberate filth in different lanes. Loopback, MIDI and USB bus power add flexibility without turning the desktop into a cable-based hostage situation.

Solid State Logic SSL 2+ MKII

Four balanced outputs with 120 dB dynamic range, next-generation 32-bit/192 kHz conversion and two independent headphone outputs give exacting adult e-stim users plenty of room to separate a compatible power box from everyday listening. The physical controls are substantial, the output section is properly studio-grade and built-in loopback expands computer-audio routing when required. It has the reassuring air of equipment intended to run a recording session, a broadcast and a discreet electrical conspiracy before lunch.

Arturia MiniFuse 4

Four balanced line outputs, 110 dB dynamic range, an internal mixer and two independently controlled headphone sockets make this a sharp little routing hub for adult audio-stim users with compatible equipment. One stereo pair can handle the e-stim power box while another remains available for conventional monitoring, with virtual loopback ready for more elaborate computer setups. Two built-in USB ports help tame peripheral clutter too. Sleek, flexible and unusually well connected, it feels like kit rather than another anonymous plastic dongle.

Universal Audio Volt 476

Four-channel output, 24-bit/192 kHz conversion and a large physical monitor control give adult e-stim users a handsome way to feed high-quality stereo files into a compatible power box. The additional outputs leave more breathing room than a basic two-channel interface, while class-compliant operation supports Mac, PC, iPad and iPhone setups. Rugged metal construction and unmistakably retro styling make this less of a disposable computer accessory and more of a studio fetish object with very respectable manners.

Zoom UAC-232

Its headline 32-bit float technology is primarily aimed at recording, but adult e-stim users wanting a dedicated stereo computer output still get two TRS main outputs with physical volume control, operation up to 192 kHz and software control over routing and monitoring. There is no sprawling bank of spare analog outputs, so this suits a focused setup feeding one compatible power box rather than a miniature studio empire. Compact, unusual and pleasingly single-minded, it keeps the digital signal path away from a laptop’s bargain-bin headphone socket.

Behringer U-Phoria UMC204HD

A two-input, four-output layout and 24-bit/192 kHz conversion give budget-conscious adult audio-stim users far more routing freedom than a flimsy USB headphone adaptor. Multiple analog playback connections, including TRS, RCA and XLR, make it easier to integrate a compatible e-stim power box into an existing computer-audio setup without sacrificing every other output. It lacks boutique glamour, but it is sturdy, versatile and refreshingly free of expensive studio peacocking. Cheap does not have to mean hissy little nuisance.

PreSonus Quantum HD 2

A formidable 20 x 24 architecture, 32-bit/192 kHz operation, custom low-latency drivers and low-noise converters make this serious overkill for adult e-stim users who want a larger computer-based audio system with room to grow. Main and line outputs provide the analog connections needed for deliberate routing into a compatible power box, while Universal Control handles metering and hardware management from desktop or mobile devices. It is a black slab of unnecessary capability in precisely the most tempting possible sense.

Learn more about using external soundcards for e-stim audio files

• The official E-Stim Systems 2B audio guide explains how its microphone, mono and true stereo modes translate ordinary audio sources into stimulation across the unit’s isolated output channels.
• ElectraStim’s Audio Stim Library introduces audio-controlled electrostimulation and provides files created to produce changing rhythms and sensations through compatible ElectraStim equipment.
• Before plugging in anything more exciting than a USB cable, read ElectraStim’s electrosex safety guide, which covers prohibited electrode positions, health exclusions and the basic precautions that should never be skipped.
• Focusrite’s Scarlett Solo setup guide shows how to connect the USB interface, use its left and right monitor outputs and control the outgoing signal from the front panel.
• The official Behringer U-Phoria UMC202HD page details the interface’s USB connection and stereo quarter-inch outputs, making it useful when checking cables and connection requirements before building a computer-based setup.
• Microsoft’s Windows audio-routing guide explains how to assign a particular output device to an individual application, helping keep an e-stim player separate from browsers, alerts and other noisy digital gate-crashers.
• Mac users can follow Apple’s sound-output instructions to select a connected USB interface, adjust its output level and confirm the stereo balance before playing a WAV or MP3 file.
• Audacity’s external audio-device guide explains how to rescan for newly connected USB hardware and select it as the playback device when editing, testing or playing stereo e-stim files.