MonopriceUnity 200-Watt Bridgeable Power Amp - Class‑D Amplifier, 12-Volt Input/Output Triggers, Rack Mountable

So I've actually bought 3 of these over the last few years.#1 I used to power a pair of atmos speakers with a 12V trigger line to turn it on from the AVR.#2 I used in the living room to drive a pair of bookshelves for casual listening using using the signal autodetect. The pass through RCA inputs go to a sub.#3 I used in my home office to drive a air of bookshelves using the signal autodetect.Maybe they aren't "audiophile" quality, but they have good sound even when using them at fairly loud volumes. The power on and off works reliably both with the 12V trigger as well as the signal detect.There is a "volume control" adjustment on the back of the amp meant for adjusting peak volumes more than anything else. I'm not sure if it really adjusts the output or just attenuates the incoming signal, but its mandatory to tweak it when using the signal detect function for power on. In my office, when I'm listening to music at a low volume while I'm working the amp would occasionally cut off due to the small input signal on quieter music. So adjusting the volume on the amp down about 30-40% means I can run the input at a higher volume level to make sure the amp stays on while still keeping the speakers at a reasonable volume level for background music. And even though I'm giving up on max power, the amp still drive my 89 dB sensitivity bookshelves a lot louder than I want to listen in my office so practically I'm not losing anything.Runs at fairly minimal heat and even after some spirited use in the living room where its mounted inside a cabinet with the door shut its not hot enough to worry about.I think its a good power level and feature set at this price.

I have bought two of these to replace a different power amp with A/B/A+B switching that proved to be very lacking in power output, nowhere near what it says in the ad, even when driving just a single pair of speakers.My two Monoprice Unity 100s will be used to drive a pair of speakers in the ceiling of our dining room and a second pair out on our covered patio. For this type of service where you really don't need hundreds of watts or audiophile performance they are ideal. If you think you're getting audiophile performance from a Walmart priced (but I assure you not quality) product, think again. If you want more watts for your Atmos or rear surrounds or whatever, I would think about the more expensive 200 model, however.First of all the likes:1. Price - at $125 and change these are excellent value for money for use as a modest power amp for, say, Atmos speakers or, as I am using them "muzac" service around the home.2. Built quality - very sturdy cases, nice and solid, well finished.3. Size - very low profile and only half the width of a standard hifi box or AV receiver, meaning you can put two side-by-side in your stack without taking up too much headroom. Rack mountable too with brackets supplied.4. Heat (or lack of it) - being class D amplifiers they don't create a lot of heat, which is good.Things I don't like:1. Volume knob on the back - might be okay for "set it and forget it" use, but for balancing speakers out it may be an issue for some. There's plenty of room on the front panel for a volume knob, I can only think hiding it on the back meant they could use a cheaper one (see below).2. Volume knob is very small and needs a screwdriver to turn it.3. Volume needs to be cranked up all the way anyway so why bother?4. Speaker connections - you have to strip the wires and insert them into a block, tighten the screws down. The blocks will only take 14 awg wire at most, and you have to be careful not to let stray wire strands short out the connections - they are VERY close to each other. I have to reconnect my wires for a different reason this weekend, and I am going to take the opportunity to "tin" the wire ends with solder to give me solid ends to fit into the connector block.Sound quality? Jury's out on that one. To be fair I'm hardly using a pair of top-of-the-range hifi speakers, just modest built-ins, but I'm not expecting audiophile quality from a $125 amp either. Should be perfectly fine for Atmos or rear surrounds or muzac service though.

My cousin has an antique system with multiple speakers in 4 rooms that were driven by an old Denon receiver with a crappy speaker switcher box. The receiver's amp section died but the pre-amp outs worked fine. This was an ideal solution so he didn't have to learn a whole new system, I just tied the amp into the speakers with a new 4 speaker switchbox with impedance protection, ran the pre-outs to it, and we were back up and running with no change with how it works from his perspective.With a 12v wall wart running from the switched outlet on the Denon for the trigger it worked out great. With the small size and Class D cool running temperature it all went in the cabinet with no issues. It sounds as good as it needs to for this application.We'll see how it holds up over time, but for now I'm very happy with it.

It's pretty cheap and rack mountable but won't last more than a couple years in a commercial use. Last one went out in 15 months. We've burned through three of these and finally decided to upgrade to crown.