B-Stock SZA-2A Stereo Amp with Auto Detect and Switch

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In Stock. Ships same day M-F if ordered by 2pm Central.


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With its auto-on and ADSTM (Auto Detect and Switch) circuits, the compact SZA-2A amplifier opens a realm of possibilities to enhance your audio experience. Here are a few suggestions for how to use this unique amplifier:
Add a source that’s unique to one zone in your whole-house audio system, that can even be used when the system is off. The SZA-2A makes a great “smart” sub-zone amplifier. It has twice the power output as the SZA-1 and its auto-source-switching feature allows you to add a source that is only available to that area of the home.
Connect a zone’s Variable output from your whole-house controller (MC-66, Lync 6, Lync 12) into Input 2 on the SZA-2A. Connect a source, such as a music streamer, into Input 1. In this way, the zone can use the Whole-House Audio system just like any other zone in the house, but whenever the source plugged into Input 1 is active, that source will override what will be heard in that zone.
Imagine adding a Chromecast Audio or other WiFi streamer to Input 1 for kids’ rooms and guest rooms. Let users know which streamer is dedicated just for them and all they have to do is start streaming to it to hear the audio in that room. That is, the Whole-House system doesn't even need to be turned on and you don’t need to “teach” anyone how to use the app or keypad.
When combined with an Amazon Echo Dot and your favorite pair of speakers, the SZA-2A helps create an awesome stereo system with multiple uses:
Use as your primary stereo system. Think of this solution as a "smart speaker" on steroids. You get a more powerful amplifier, your choice of quality speakers that you can spread apart for better coverage and true stereo imaging, and an option to add a source in addition to whatever the Dot has to offer.
Use as the perfect stereo for teenagers. Most teens want something that performs more like a real stereo system than a plastic stand-alone “smart speaker”. In addition to the Dot, let them add whatever second source they’d like (phone, music streamer, game system, TV, etc.). And why is this the perfect solution for you as well? Because you can always interrupt what they are listening to by “intercoming” into the room with Alexa’s “drop-in” feature. No more shouting to get their attention!
Stream the same source, in sync, into multiple smart-stereo kits. Install multiple smart-stereo kits throughout your home to create a simplified wireless whole-house audio system. For party mode, use the Alexa app to stream the same source through all of your Dots simultaneously.
In addition to ADSTM, the SZA-2A also includes an Auto-On feature. Use this option to “set and forget” the amplifier. When no source signal is detected from either source input, the amp will go into sleep mode drawing minimal power. When either source is detected, the amp will automatically power up and start playing that source.
It doesn't have to include a Dot! The SZA-2A works with any two audio sources. Connect a TV and a chromecast audio to create a stereo system perfect for a guest room (or any room for that matter) that's super easy to use. Want to listen to music? Stream through the chromecast. Want to watch TV? Turn on the TV. The combination of audio sources is nearly endless. The key is the SZA-2A's ability to both auto-power-on and auto-detect and switch between those two sources!
Some notes about setting up the SZA-2A:
The SZA-2A will switch to the primary source whenever the input signal reaches a minimum threshold (around 7mV). The amp will switch back to the secondary source whenever this threshold is not met. When both input sources are simultaneously playing, the auto-switching works best when the Input 1 signal is consistently above the threshold.
For the Dot, we recommend setting its volume around 7-10 by default. A setting of 10 (max) is equivalent to a fixed level output from traditional audio devices like a CD player. If you stream music through the Dot at very low levels, you will want to turn off the secondary source input while streaming or increase the Delay time on the SZA-2A to prevent the amp from auto-switching back to source Input 2.
For most users, setting the Delay knob to near minimum will work best with Alexa.
Volume is set one time on the amplifier itself (and then adjusted using the source's volume control). Connect your Dot to Input 1 and play an audio stream at volume 10 set on the Dot (just say, “Alexa, play my music at volume 10”).  Then, while listening to music, set the amp volume level to the maximum you’d ever want in that room. At that point, you should never have to adjust the volume on the amp again.  Volume for the Dot is controlled at the Dot or by voice, and volume for the other source is controlled by that source (note: when using a TV, the TV must have an analog variable output).


  • 2 stereo RCA inputs; Input 1 is PRIMARY, Input 2 is SECONDARY
  • 40 Watts per Channel at 8 ohms, both channels driven
  • 70 Watts per Channel at 4 ohms, both channels driven
  • Total Harmonic Distortion (THD) .07% at rated power
  • Frequency response 10 Hz - 40 kHz (-3dB, 1 watt)
  • Dimensions (HXWXD): 2 1/4" X 8 3/4" X 7 3/4" (please allow a minimum 1" of space behind amplifier for cables)
  • Auto-on stand-by power: 5 watts


Volume is set one time on the SZA-2A, essentially limiting the power output you want sent to the attached speakers. After that, volume for each of your two sources is controlled by the sources themselves. Unlike a traditional receiver that accepts fixed line-level inputs (think DVD/CD players, cable boxes, etc.), and thus requires a variable master volume control, most of today's streaming sources include their own variable volume adjustment allowing the amplifier level to remain fixed. That is why if you are using an SZA-2A to power speakers in a zone in your Whole House Audio system, we instruct you to connect Input 2 to the variable output (not the fixed output) on your Whole House Audio system. You can then adjust the volume level for that zone either using the mobile app or a keypad. Similarly, if using a TV as a source, it requires that the TV has a variable analog output, so that you can adjust the TV volume using the TV's remote control.

Yes and No. Unlike the Dot, the Google Home Mini does not include an audio output. You can pair the Home Mini with a Chromecast Audio and then connect the Chromecast Audio’s audio output into Input 1 on the SZA-2A. In this way, you can issue a “Hey Google” command to the Home Mini to stream music out of the Chromecast Audio. However, if you ask a simple question like “Hey Google, what’s the weather forecast?”, the answer will come out of the Home Mini, not the Chromecast Audio. Maybe at some point in the future Google will provide a software option to fix this, but until then we will continue to recommend the Dot.

In addition to auto-source switching, the SZA-2A also includes an auto-on feature. Use this option to “set and forget” the amplifier. When no source signal is detected from either source input, the amp will go into sleep mode drawing minimal power. When either source is detected, the amp will automatically power up and start playing that source.