Fosi AudioBluetooth Subwoofer Amplifier 2.1, BT30D Pro Subwoofer Amp with TPA3255 Chips 165W x2+350W & Bass Treble Control, 2.1 Channel Sub Amplifier for Desktop/Outdoor/Bookshelf Speakers

My goal was to setup excellent sounding backyard garden speakers. First a quick story about what led me to this incredible Fosi amp. I found a terrific "all in one" setup from OSD Audio that was a Bluetooth capable powered outdoor subwoofer with 2 channel satellite powered outputs (can power up to 4 satellites total). I purchased 4 of the OSD Forza 4" satellites, which are AMAZING commercial grade outdoor speakers with separate woofer and tweeter in each speaker. The system sounded great until the speakers and sub started crackling and popping, even when nothing was connected. It turned out water penetrated the sub enclosure, the amp inside the enclosure was shorting out, and the OSD folks were fantastic about sending me a replacement. I setup the replacement and thoroughly enjoyed listening to the setup for over 5 hours the day I installed the replacement. The next morning I heard the same crackling and popping, AGAIN! This time I broke open the sub enclosure to figure out what went wrong, and the OSD plastic logo on the very top of the sub enclose is not sealed with silicone like the rest of the sub enclosure is sealed up. My sprinkler system, or almost daily rain we get here in New Orleans penetrated that weakness (water will ALWAYS find a way), and the amplifier sits immediately under the nameplate inside the enclosure and got really wet. Amazingly, the OSD folks were REALLY kind enough to send me another replacement, but this time I shared with them the cause of the malfunction, and hopefully they will seal that part up if you order from them. I received the new OSD replacement setup, put lots of silicone on top of that OSD nameplate on top of the sub enclosure, and put that setup by my pool, and no problems yet!I shared all of this because that 2nd replacement OSD sub that I broke open I repurposed by clipping off the internal wires of the amplifier, satellite speaker outputs, etc. and converted the OSD sub into a passive sub now needing power from another source, and naturally sealed it up really good with lots of silicone. I searched long and hard for "outdoor" 2.1 or 4.1 amplifiers and this Fosi seemed to check all of the boxes, except that it wasn't waterproof. I wanted to put a quality amplifier in an outdoor weatherproof box to avoid the issues I had with the OSD sub setup. After getting it all hooked up, and tuning the amp (adjusting bass, treble, sub crossover to blend w/ the satellites, sub volume, and amp volume I leave in the same position sealed up in the weatherproof box to use my phone's volume when connected via Bluetooth), this Fosi 30D Pro amp sounds every bit as good, if not better, than my home theater setup with $1,000 Yamaha receiver, Paradigm speakers, and $2,000 SVS subwoofer. I actually go sit in my backyard now to listen to my garden speaker setup over my home theater setup it sounds so well balanced and that good. I play music (piano and trumpet), and definitely have an "ear" for music, and this Fosi amp is the real deal, especially when connected to the right kind of high quality speakers. One shortfall about the amp when sealed up in the weatherproof box is that the amp only has a manual lever switch on the unit itself to turn it on or off. Obviously it's not a good idea to leave the amp "on" at all times, and it's very inconvenient to open the weatherproof box every time you want to turn the amp on or off. My solution was to connect the power supply cord of the Fosi amp to an extension cord (bought an outdoor cable cover to protect that connection), and plugged the end of the extension cord into a short extension cord that has an outdoor "on/off" switch, which is then plugged into an outdoor electrical outlet box. Now, whenever I listen to the garden speakers with the Fosi amp, I just walk over to the easily accessible electrical outlet and flip the switch to "on," and my Bluetooth on my phone finds the Fosi amp in no time to connect, and I'm enjoying beautiful, full, rich music...easy peasy! And when I'm finished listening, I just walk over to the switch by the outdoor outlet and flip it to "off." This way the Fosi amp is only "on" when I'm actively listening to it. Hopefully that trick will give it plenty of life! I'll put a link for all of these things below.Here is the box I purchased to house the amp and power supply outdoors: https://www.amazon.com/gp/product/B0CP5RL1PZ/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&th=1Here are the OSD Forza 4" satellite speakers I used for the system: https://www.amazon.com/OSD-Landscape-Mountable-Commercial-Resistant/dp/B0916DWXB5/ref=sr_1_2?crid=11056H4LSDN72&dib=eyJ2IjoiMSJ9.gXdDGu8oqU6XiOzDj8u_3rcA2hslL7UTIJmBiwG7-2hbrwNmy7k6LoCGQX15P6aautXVnUXHOW8BoAb_JmqIEb2bFIvZpUJ8T1ZWOvLHuwd3LDQPvNp6VHNJ-9AQlrunzEQWPpHtbrz0H-eBII_sl0FIgOVJnWu6vg6xTF7A6VKLvuDrKV8pffWRfNN1eoGQYeCVYvwJdTFHPFHNTHUf3gbmiawF4akuyNX8olshjtg.SEPJM2UZxVcC-f0JL_dDnT_TxCJ0EFLeuaDYJ76bdYQ&dib_tag=se&keywords=forza%2B4%2Bspeaker&qid=1719723606&sprefix=forza%2B4%2Bspeaker%2Caps%2C115&sr=8-2&th=1Here is the passive outdoor sub I would recommend to use with the Fosi amp: https://www.amazon.com/Forza-Outdoor-Weather-Resistant-Subwoofer/dp/B07R3FCV5K/ref=sr_1_1_sspa?crid=C9VIY16QR2TA&dib=eyJ2IjoiMSJ9.-gZpe9alIyquiwEciwwy_th2Z8h9E_FxalkH-E3bEjzcdF4a1gSljKYLatMM1MxJovLfQGnJmGzyVY0k8KcsB_K5VPKrbtmKJCDpPPnrGADUW_5iXfCiSmPhH0aB1nxnLJU696Gp7y4pfE5CufG9q8rjA26q7mi03W09ruL-tgn6bejQo1-Eg7ghcqR41wmPvbJFHa5iNOSbiDJ5ZKTOzgmqbhdywOyYWyDDSnvB70g.svHb9CJqXcq5JPseVJzdJpKNc1FxKVsuKGJGk9x6V0w&dib_tag=se&keywords=OSD+outdoor+subwoofer&qid=1719723686&sprefix=osd+outdoor+subwoofe%2Caps%2C131&sr=8-1-spons&sp_csd=d2lkZ2V0TmFtZT1zcF9hdGY&psc=1Here is the outdoor "on/off" in-line switch on short extension cord: https://www.amazon.com/gp/product/B0BP7XL3MH/ref=ppx_yo_dt_b_asin_title_o09_s00?ie=UTF8&th=1Here is the OSD "all in one" active / powered 8" subwoofer with powered satellite outputs if you're interested (remember to put silicone sealer on top of the OSD nameplate to really seal it well): https://www.amazon.com/dp/B089DTP3MX?ref=emc_p_m_5_i_atc&th=1

I bought the Fosi amplifier because I have my NAD amplifier connected to two Cambridge Soundworks sub woofers but I wasn't getting much bass from the 8" woofer. I am very impressed by this amplifier, I can increase the volume of the woofers separately from the Yamaha two way speakers that are mounted in the same cabinet. I can now hear instruments on Jeff Beck's Blow by Blow LP that I've never heard before.

I replaced another Amazon amplifier board offering with this Fosi after growing tired of the audio delay and dropped audio.The amp is powering two five and one quarter inch Rockville bookshelf speakers, a passive Rockville eight inch sub, and a Fosi powered active eight inch Planet Audio sub.No delay using Bluetooth, no dropping into 'standby mode' when the audio input drops below a certain level.I did use a 10A 48vdc power supply in order to ring out the most power I could from this amp.I also added active cooling as the amp does run hot at 48vdc.

I've been using this amp for 6 months on my PC, first just plugging it into an RCA to 3.5mm audio out, then plugging it to the Fosi K5 Pro (that one's still a story in progress, has some issues but they don't matter to the amp).This amp can very easily and comfortably drive a pair of JBL Control 25AV and JBL Control 1 speakers. No clipping, no distortion, just pure sound with the knob at 50%. For small speakers like that, it is very good. I did not try the Subwoofer output, i actually bought it thinking i'd need a sub with my speaker setup, but both speakers have very nice bass already, and i'm not that much of a bass head so i will be skipping the sub. The BT connection is very nice, although i had to rig my own BT antenna since the one that came with the unit offered too much range. Still, it is always better to have more than to have less, and BT is easy to adapt to a shorter antenna run, so i had no issues with it. The unit definitely gets hot to the touch, but never too hot that it burns me (i can place my hand on the top and feel it is warm), and it is not like it would even get to start a fire if you put something plastic on top of it (i put my Kindle on top of it by accident and left it there for 3 hours and neither the amp nor the Kindle showed any damage). And i got this unit with a very nice 20% discount coupon, so for under $100, this amp is really awesome.Now, for the cons. If you have big-ish speakers, you will definitely need more juice. I tried this amp to a pair of Pioneer CS-503, a pair of speakers rated for 50w @ 8Ω as per the label on the back (and as per Fosi's power table, this amp should be good enough for them on the stock power supply) but are really big beasts, and this amp definitely sounded less powerful on them. Still no major issues, but it sounds like this could use a bigger power supply. On that front, it came stock with a 32V 5 A power supply... and that's a really big mistake, since the voltage range is really small. This unit can only accept up to 36v power supplies, while most other amps from Fosi take up to 48v power supplies. This amp should come stock with the bigger power supply, especially since i doubtr the same 32v 5A power supply could deliver the same quality if i added a sub to it. And to make things worse, the 36v power brick is not even sold by Fosi! They sell 32v and 48v, but no 36v, so unless you get a random power brick, there's no way to juice up this amp. Lastly, having only automatic BT selection can be annoying if you already are listening to the RCA input. It happens to me when i turn on my laptop, it auto latches on the BT and my PC gets silent until i can disconnect it again on my laptop. It is a relatively minor annoyance, but when it happens at least once a day for 6 months, there's no way to even ignore it. Having a BT selection switch/button would be a great help for this.Overall, if you get this amp for under $100, it is a steal for small to mid-size speakers. And the fact that it accepts both RCA and BT inputs makes it extremely versatile. However, there are definitely better options if you need more juice, don't need a subwoofer, or want more control. Fosi makes some other excellent amps, and other brands too, but for $100-110, this amp definitely loses to those other options as other options do deliver better audio quality, are cheaper or can accept a bigger power supply for more oomph.

This thing is awesome! I do recommend getting the more powerful adapter for it if you’re running big speakers like I am. I have it hooked up to a 8 inch ds18 subwoofer and 6.5 inch component speakers with their own crossovers. IT GETS LOUD!!!!! I’m amazed how this little amp can power this subwoofer. I can feel it in my chest when I stand close to it. And it’s crystal clear sound when turned up. Hands down worth every penny! Easy set up. No problems at all.

I tried two other bluetooth amps to power a sub and a tower I put on a moving dolly to move wherever I wanted some tunes around the house. This one actually has the power to play without cutting out while powering an 8-inch sub and the 3-speaker tower. Twice the price of competing products but it actually has it where it counts.