This page lists American companies that make the control center of a high-end audio or home theater system: surround sound processors that decode immersive formats and send them to many speaker channels, room correction, DACs that turn digital audio into analog, and preamplifiers that switch sources and set the volume before the signal reaches the power amplifiers.
Processors are some of the most complex products in home audio. A US maker may design its own circuit boards, software and analog stages and assemble and test every unit here, while buying chips, displays and some modules from other countries. Each listing says what work is done in the US and names imported parts when the company or another source states them.
For power amplifiers see Amplifiers, and for loudspeakers see Speakers.
More types in this section ↓
Theta Digital makes high-end audio electronics for music and home theater, sold through dealers. Its flagship Casablanca Va music and cinema controller is an 18-channel immersive surround processor with Dirac Live room correction (six stored filter setups), modular DAC and input cards, and a Reference Balanced Analog Input Board with XLR inputs and an analog direct mode. Casablanca processors sold since 1996 can be upgraded to the current Va version. The line also includes the Prometheus monoblock amplifier (500 watts into 4 ohms, with a 1.44 kVA toroidal transformer in a linear power supply), the modular Dreadnaught D multichannel amplifier (225 watts per channel into 8 ohms) and the Generation VIII Series 3 balanced DAC preamp. Theta introduced the first outboard digital-to-analog converter, the DS Pre, in 1986, and has been a division of Amplifier Technologies, Inc. (ATI) since 2007.
Made in: Montebello, CA (design and manufacturing facility). Each Casablanca is assembled, made to order and fully tested in the USA, and its rear panel is marked Made in U.S.A.
Imported: the Prometheus and Dreadnaught D amplifiers use Hypex Ncore class D modules, designed by Bruno Putzeys at Hypex in the Netherlands, combined with Theta's own linear power supplies.
Source: Theta Digital, Casablanca Va · Theta Digital, 2024 · Stereophile, 2015, checked 10/2026
Montebello, CA
Processor makers by state
- California: Theta Digital (Montebello), Casablanca music and cinema controllers and DAC preamps
What a processor does
- Surround decoding: a surround processor decodes formats such as Dolby Atmos, DTS:X and Auro-3D and sends each channel, including overhead and wide speakers, to its own amplifier channel.
- Room correction: systems such as Dirac Live measure your room with a microphone and adjust each speaker's output to smooth bass peaks and reflections.
- Digital-to-analog conversion: the DAC section turns digital audio from discs, streamers and computers into an analog signal. Balanced designs use separate converters for each phase of each channel to lower noise.
- Preamplifier: the preamp selects the source and controls the volume. A good analog volume control or analog direct mode keeps the signal from being converted back and forth.
Choosing a processor or preamp
- Channel count: count every speaker you plan to use, including height and wide channels and subwoofers. A processor with more channels leaves room to grow.
- Upgradability: modular processors with replaceable input, DAC and video cards can be updated for new formats instead of replaced.
- Connections: balanced XLR outputs suit long cable runs to separate power amplifiers; check that the digital, analog and HDMI inputs match your sources.
- Receivers vs separates: an AV receiver combines processor and amplifier in one box. Separate processors and amplifiers let each part be built without compromise and upgraded on its own.
Reading "Made in USA" on audio electronics
Under Federal Trade Commission rules, a plain "Made in USA" claim means all or virtually all of the product is made here. Most audio processors built in the US use imported chips, displays or modules. The listings on this page say what work happens in the US and name imported parts when a source states them.
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A company may be based in the USA while making some products elsewhere. Check the manufacturer's own site for where a specific product is made.