ALTO Stealth 1 Mono UHF XLR Wireless Audio System, Transmitter and Receiver for Powered Speakers, Mixers and Dynamic Microphones

I can report on the question: How well does it do with intermediate walls? This is obviously very dependent on the architecture and wall construction, but perhaps the following will help. I have a configuration where my primary HiFi system is separated from a secondary HiFi system by at least 3 walls for the direct path, plus one that may be intercepting the EM wave tangentially, and with a large refrigerator and double wall oven stack also in the general path.Because the exact path, or shape of the wavefront including diffraction effects, is not easily determined by me, I'll just note that the walls are mainly 2 x 4 with sheetrock covering. Many incorporate plumbing and electrical wiring. One near the transmitter has a glass covered picture in the direct path. Total distance (as the EM wave flies) is about 66 ft, slanted downward to a lower split level. If this were a pure air path, one would be well within the rated 200 ft performance limit, but with the walls it was a bit of a stab in the dark as to what performance would result.The receivers are indicating four bars reception. Sound is excellent (within the limits of all the components that are in the path). Receiver scan led to channels 001 and 002 being selected, so operation is just above 540 MHz. Standing close to the receivers in the direct path seems to have no effect on indicated signal strength.Additional items needed for my purpose included two Klark Pro 2 XLR splitters to intercept the audio signal between pre-amp and amplifier at the transmitter end, two Sescom AUD-XLR-RCA 1 Channel XLR to RCA Balanced To Unbalanced Audio Converter modules for the receiver end, and various interconnecting cables.One advantage of this direct RF approach over WiFi schemes is avoidance of signal delays; that is, speakers are synchronized. Intermediate listening locations do not have echo like sound.

I needed this for two specific applications: wedding ceremonies and satellite speaker situations. In both settings, I don't use extension cords and either can't or don't want to run XLR cable. The Stealth 1 Mono system is ideal for this:It sets up fastIt's easy to useIt works.I've spent a lot of time with the Stealth 1 Mono wireless system. I've tried it in many situations. When you follow the instructions EXACTLY, it works perfectly: Set the speakers where you want them. Turn the transmitter on first and THEN the receiver. IF you turn the receiver on first, the whole thing becomes intermittent.I've tested the battery life twice with rechargeable batteries. They lasted 4.5 and 5 hours before the wireless turned off. That's more than enough time for wedding ceremonies, cocktail hours and short gigs. I've also ran it 80' apart without any issues. I haven't needed it to go further than that, but Alto says it will go 100'. I've also used it with the output on a mixer to the speaker and it worked flawlessly.UPDATE: I had the same static issue as HGDJ below. But it only happened when I was using this with a Bluetooth input on the speaker to send music to it on a test. As soon as I plugged the music directly into the speaker input via a cable and sent the signal out to the other speaker via the Stealth 1, the static went away and it worked perfectly. Maybe you can't use Bluetooth AND the Alto Stealth 1 at the same time?The Alto Stealth 1 Mono solves my problem perfectly. Would I use this with the band in a critical "this can NOT fail" kind of situation? I don't think so. If I wanted a wireless speaker system for the bands FOH system, I'd go with the Alto Stealth Wireless Pro.

I was very excited about receiving this wireless system. As soon as it arrived, I unpacked it, read the instruction manual and set everything up.I let the receivers scan for available channels and synced the transmitter up accordingly. Then I powered up my speakers and to my unpleasant surprise immediately I heard a very noticable mix of hiss and rumble.Tried the different squelch settings to no effect. Unplugged the receivers and instead hooked up my xlr cables, to make sure nothing was wrong with my speakers, unlikely for QSC speakers, but wanted to make sure it's not a defect from my side. Connected to the xlr cables the hiss/rumble disappeared. So I reconnected the stealth mkII receivers again to try searching for another channel. Now it took them over a minute to search and when they found and set themselves to supposedly free channels my speakers almost blew out my eardrums because all that came through was an extremely loud interference noise.Luckily I turned the speakers off before they could be damaged.Syncing up the transmitter to the channels didn't help. Now it just added the occasional burst of interference noise.I also tried to only use one receiver to make sure they were not interfering with each other, even though they both ran on different channels and properly set to left and right.The transmitter was also a mere 6 feet away with direct line of sight, so no obstruction nor too far of a distance of any kind.Knowing how frequencies can interfere with each other on live events, especially when other DJs or musicians set up their wireless equipment in neighboring rooms, I can absolutely not rely on these. Imagining a bride, a celebrant or just anyone standing next to a speaker when it's silent or playing background music, then interference happens and shoots out this ear piercing interference pattern into a person's ears, I'd lose credibility, potentially damage my speakers, because I won't be standing right next to them, to turn them off right away, potentially a lawsuit for bodily injury in form of hearing damage(mine are still ringing as I write this review) and definitely lose recommendations for potential new clients.I so wish the stealth system had worked but if it already gives me these problems at home, in a semi rural area, it'll definitely give me more problems in crowded places. I cannot take that risk and sadly will have to return them back to Amazon.