This little amp is amazing. I use it only for bluetooth. I have 2 nice KEF bookshelf speakers attached, and it works flawlessly. The volume, bass and treble work perfectly. We had this onsite during months of house construction and it was the bomb.

I installed this amplifier in a modern pinball machine to improve upon the sound provided by the machine's built-in amplifier. Wow, it made a dramatic difference! I love that it has more than enough power to produce deep, rich bass in a JBL Stage 82 subwoofer while providing strong midrange and crisp highs in a pair of Kicker CSC5 coaxial speakers. I also like that the bluetooth functionality works reliably and seamlessly (when a bluetooth source is detected, it instantly switches from the wired input to the wireless input). Amazing for such a small amplifier!

Perform well above my expectations! As my Klipsch PM2.1 internal amp blew due to fried capacitor, decided to try this amp and it packs more power than before.

EXTENSIVE testing trying to figure out "why" this great little amplifier didn't punch out the power. The subwoofer amp kept clicking off at higher volumes with the stock AC/DC 32v adapter. I ended up using a 12/24v to 36v step up booster and a 24v (10a) AC/DC adapter (Output is 36v, 10-amps). I tested the max current draw at full power - about 8.6 amps! The stock adapter is rated for 5 amps. Duh? That was the problem.This amp runs at 36v all day long...and a little warm. But, if you want full power and not having the subwoofer amplifier chip kicking off all the time -- either get a 32v (10-amp) adapter or even better 36v (10-amp) adapter. The good thing, a simple turn off/turn on resets the amp (subwoofer amp will reset).The Bluetooth 5.0 is phenomenal...excellent and fast connectivity.The fidelity and sound quality is totally quiet and pure. THD ratings are probably dead on accurate. It really plays beautifully all the way up to full power.The pre-amp out 3.5mm jack is a brilliant addition -- I tested it and it works like vintage equipment. Bluetooth connectivity is not affected. Linear with mains. If you ever wanted to add an active sub via this jack, you can -- it is full range.AUX input works -- no issues with low power pre-amp section like many other of these little digital chip amps. Bluetooth 5.0 is set HIGHER than expected -- NICE job Fosi! So many are set too low.Use banana connectors for your speaker wiring -- 4-8 ohm for mains, 4-ohms plays best.BOTTOM LINE - feed this little guy 36v and 10-amps of power and it is one helluva performer. It will deliver some nice subwoofer bass if your subs are decently efficient. PA sub cabs @ 4-ohms work best. Car subs are not that efficient (low SPL per watt). For those just wanting a lower volume 2.1 home AV system (like for watching TV or on a computer), no need to upgrade the included AC/DC adapter. For me, why by a Corvette and drive it like grocery getter Camry?

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

Having just built a new home, I’d installed an in-wall subwoofer and a few decent ceiling speakers in one room. I needed a small, adjustable amp capable of taking care of the 3 channels, with a built-in crossover for the sub. Enter this little beauty - it has huge power for such a tiny box, and with a good source is a remarkably good sounding amplifier. I’ve built amplifiers for decades, from simple transistor amps, to vast Hexfet ones, to hybrid ones with very high end standards. I couldn’t come close to this kind of value, and the quality is really very impressive too.Easy to set up, plenty of power, clean sounding, bonus of Bluetooth connectivity for the times that might be handy.Bottom line - excellent value!

Funciona muy bien

My search for a budget friendly amplifier led me to Fosi BT30D PRO. Read reviews here and on multiple audio forums online about this amp. After seeing positive responses from users, went ahead and purchased one . Paired this with polk audio XT15s Bookshelf speakers.Main audio source - Smartphone.Build quality of the amp is very good. Bluetooth connectivity was smooth. Kept all settings of amp at mid level. Player eq flat and volume at 60. Initial impressions - Good👍. Decent bass, clear vocals and treble. Overall its a Warm sounding amp, matches well with polk xt15s. Total Value for money product.*Will definitely recommend this amp*

omdat je de totale controlé hebt over het geluid en hoge en lage tonen en zelfs de frequentie en volume van de subwoofer is deze model een van de beste, ik heb het zodanig aangepast dat ik zelf een centrale speaker kon installeren met een krachtige bose sub woofer . Het is zeker een aanrader ik heb eentje beneden voor mijn Tv en ik heb eentje boven in de geluid studio voor mijn Krk speakers prachtig geluid.

Compared to the BT30D non-Pro, the Pro version is quite a bit longer and heavier (430g vs 620g).The knobs are made of aluminium, different texture compared to the no-pro, a bit more resistance to turn than the. Same throw switch used to power on.The 3.5mm PRE OUT is full range.Bluetooth will be always-ON so your neighbor can hijack your device just like the non-pro version. Remove the antenna to prevent this from happening if you don’t use BT. Come on Fosi Audio, please fix this.The amp has a 4” tall BT antenna, again it's better than the 7” incher of the DA2120C that looks like a CB radio... Please give us the 1 incher for future products, for once the smaller the better.BT uses an ATS2853 chip that is also found on the BL20A.How does it sound?I did a comparison with Onkyo RZ50 pure output mode (airplay), Aiyima T9 (BT), and the BT30D non-Pro (BT). All using RP5000F towers, with an amp selector switch.Right away there’s a BIG difference between the non-Pro and the rest.The Pro version is much more dynamic, the voices are clearer, bass is more present and punch harder.I honestly cannot tell any audible difference between the RZ50 and the BT30D Pro. The T9 sounds only a tad warmer (thx lamp); Even that it was really hard to tell and it depends on the song being played.The Pro version sounds definitely better than the non-Pro.To test the passive sub output, I hooked up my gutted Z2300 logitech subwoofer, it works wonderfully and has a very capable output. However, I didn't like the sub crossover control, the adjustment doesn't feel linear. There are no frequency indications on the knob, it can only be tuned by ears.The muscle: TPA3255 x 2:PSU idle voltage: 32.3VPower adapter output @ 8ohm load current and voltage, 125W:Same 32V5A adapter used for multiple models. No sparks occurred while plugging in the DC plug compared to the DA2120C I've tested, I made multiple attempts to make sure this is repeatable.Here I am trying to figure out the max usable volume before getting a bad shaped sine wave, The volume knob is at 3 o'clock, BT reference volume maxed out on my mobile device, no EQ, no tone.L & R Channel, 8 Ohm load, 1000hz tone, 26Wrms per channelL & R Channel, 8 Ohm load, 1000hz tone, clipping at 60WrmsL & R Channel, 4 Ohm load, 1000hz tone, 40Wrms per channelL & R Channel, 4 Ohm load, 1000hz tone, clipping at 100WrmsSub channel @ 4 Ohm load, 75Wrms:Sub channel @ 4 Ohm load into clipping, 121Wrms:Noise, tested with max volume:BT30D non-Pro, audible hiss from speakers during powerup, circuit shuts off when no input signal for 5 secs to prevent constant hissing.BT30D Pro, barely audible hiss from speakers, you have to stick your ear on the tweeter to hear it. no circuit to shut off the signal, it's not needed because it is not audible sitting away from speakers.The TPA3255 chips are hungry AND efficient. If you can feed them, they will put out a respectable amount of power for its size. You can upgrade to a 36V power adapter if you are looking to squeeze more juice out of it. It seems most of the manufacturers using this chip have set their bottleneck to the power adapter. If you are looking for a 2.1 amplifier with passive sub output, look no further.The BT30D Pro is way better than the non-Pro version.Pros:Great build qualityExcellent sound quality, to my ear it’s on par with the Aiyima T9 and RZ50Low noise floorRuns cool and efficientCons:Cannot turn BT offSub frequency needs indication and more linear tuningSmaller BT antenna please