MC351 from Fosi Audio arrived. They tried the proven recipe based on the TPA3255 but added an integrated DAC and a VU meter this time.
Integrated DAC means it can accept a various type of inputs. Its RCA input is just one, but you can connect Opt, Coax, USB, Bluetooth.
One thing I noticed in addition to the cute aluminium chassis, was the nice implementation of input selection. It remembers the last input it used. If you switch it off and switch it back on, it will stay at the same input. It is a nice touch. I have seen many cheap audio products revert to the default option when turned on, which is very annoying. Fosi did an excellent job here.
Bluetooth was also implemented very well. After my TV successfully paired with the MC351, I pressed the "Mode" button to switch to Bluetooth. The TV sound came out of the audio system as expected. Now the real test. What happens if I switch the input to something else, for example, optical. We want the TV sound to come out of the TV speakers, as the amp is now playing the other input. Yes, it did. The amp quickly unpaired from the TV, letting the TV sounds come out of the TV speakers. If it were poorly implemented, it could have held up the Bluetooth connection, inadvertently muting the TV sound. It saved me from having to fiddle with the remote control and navigate TV menus to unpair the amp, which was great. Finally, when I switch back to Bluetooth, the amp immediately pairs with the TV again and plays the TV sound seamlessly. I have seen many products fail to do this simple thing!
Another thing I liked is the automatic standby feature. It automatically goes into standby mode after 2 minutes of no audio signal - it will help my power bill as I often forget to turn off the amp.
The "Mode" button was a little difficult to play with in a dark room. Input labels are not illuminated, and the little dot LED next to the label was not bright enough to help me read the label.
The VU metre is a nice touch. It is mesmerising to watch the movement of the needle. However, the volume has to be reasonably high to see most of it. Imagine yourself sitting alone at night, a glass of whiskey in hand, and your favourite jazz track playing. But you don’t want to wake up the family, so you set the volume low. Sadly, the VU metre is not working as hard when you kinda want it the most.
I opened up the case to examine the quality of components and upgradability. Most components are surface mount, except for the electrolytic capacitors. One thing I instantly noticed was the beefy 4700uF reservoir capacitors. The inductors appear to be from Sumida. Unlike Fosi’s other recent products (e.g., V3, ZA3), I couldn’t see premium brand components like Nichicon and WIMA capacitors.
I wanted to see if it allowed opamp upgrades, but it didn’t look promising. I spotted 8 NE5532 op amps, directly soldered onto the surface of the board.
A separate board is the DAC and Bluetooth. I was unable to see what lies under this board as I failed to undo the screw.
The heatsink is large. The chassis is a lot bigger than typical Fosi little amps, and plenty of space inside should help cooling. The caps are rated at 50V. If you use 48V power supply to squeeze more oomph, these caps will be driven a little hard. I am happy with the standard 32V power though.
This is a 2.1 channel amp, and can drive a passive sub. I think it will be tricky to find a sub that matches the sensitivity of the speaker set. I'm getting an active sub and will use the 3.5mm pre-out connection. I think an active sub with a crossover control and its own volume knob will be easier to get the right blend.
The Fosi Audio MC351 is probably not intended to please critical audio connoisseurs. In comparison to the highly regarded V3 and ZA3 amps, I can see Fosi made some compromises to add more features and convenience. Don't get me wrong, it is a very capable and formidable audio engine. The magic of the TPA3255 chip continues. It is an all-in-one compact amp that pleases your eyes and ears. .
Integrated DAC means it can accept a various type of inputs. Its RCA input is just one, but you can connect Opt, Coax, USB, Bluetooth.
One thing I noticed in addition to the cute aluminium chassis, was the nice implementation of input selection. It remembers the last input it used. If you switch it off and switch it back on, it will stay at the same input. It is a nice touch. I have seen many cheap audio products revert to the default option when turned on, which is very annoying. Fosi did an excellent job here.
Bluetooth was also implemented very well. After my TV successfully paired with the MC351, I pressed the "Mode" button to switch to Bluetooth. The TV sound came out of the audio system as expected. Now the real test. What happens if I switch the input to something else, for example, optical. We want the TV sound to come out of the TV speakers, as the amp is now playing the other input. Yes, it did. The amp quickly unpaired from the TV, letting the TV sounds come out of the TV speakers. If it were poorly implemented, it could have held up the Bluetooth connection, inadvertently muting the TV sound. It saved me from having to fiddle with the remote control and navigate TV menus to unpair the amp, which was great. Finally, when I switch back to Bluetooth, the amp immediately pairs with the TV again and plays the TV sound seamlessly. I have seen many products fail to do this simple thing!
Another thing I liked is the automatic standby feature. It automatically goes into standby mode after 2 minutes of no audio signal - it will help my power bill as I often forget to turn off the amp.
The "Mode" button was a little difficult to play with in a dark room. Input labels are not illuminated, and the little dot LED next to the label was not bright enough to help me read the label.
The VU metre is a nice touch. It is mesmerising to watch the movement of the needle. However, the volume has to be reasonably high to see most of it. Imagine yourself sitting alone at night, a glass of whiskey in hand, and your favourite jazz track playing. But you don’t want to wake up the family, so you set the volume low. Sadly, the VU metre is not working as hard when you kinda want it the most.
I opened up the case to examine the quality of components and upgradability. Most components are surface mount, except for the electrolytic capacitors. One thing I instantly noticed was the beefy 4700uF reservoir capacitors. The inductors appear to be from Sumida. Unlike Fosi’s other recent products (e.g., V3, ZA3), I couldn’t see premium brand components like Nichicon and WIMA capacitors.
I wanted to see if it allowed opamp upgrades, but it didn’t look promising. I spotted 8 NE5532 op amps, directly soldered onto the surface of the board.
A separate board is the DAC and Bluetooth. I was unable to see what lies under this board as I failed to undo the screw.
The heatsink is large. The chassis is a lot bigger than typical Fosi little amps, and plenty of space inside should help cooling. The caps are rated at 50V. If you use 48V power supply to squeeze more oomph, these caps will be driven a little hard. I am happy with the standard 32V power though.
This is a 2.1 channel amp, and can drive a passive sub. I think it will be tricky to find a sub that matches the sensitivity of the speaker set. I'm getting an active sub and will use the 3.5mm pre-out connection. I think an active sub with a crossover control and its own volume knob will be easier to get the right blend.
The Fosi Audio MC351 is probably not intended to please critical audio connoisseurs. In comparison to the highly regarded V3 and ZA3 amps, I can see Fosi made some compromises to add more features and convenience. Don't get me wrong, it is a very capable and formidable audio engine. The magic of the TPA3255 chip continues. It is an all-in-one compact amp that pleases your eyes and ears. .
Last edited:
