Question 1

How can this amp deliver 200w (output power: 50w+50w+100w) if the power supply only delivers 100w? at the same time it says the psu is ’matched’?

Accepted Answer

I believe some of the specs for this amp are inaccurate and I'm not sure what the actual ratings are. Regardless, I have been running this amp for a year with speakers from a 540W Sony MHC-EC909IP https://www.amazon.com/Sony-MHCEC909iP-System-Discontinued-Manufacturer/dp/B003GZDB1Q after the main unit broke. This amp drives the speakers just as well as the Sony unit and I was happily surprised with its performance. Again, Im unsure of the actual specs, but I wanted to give you a reference of the amps actual capabilities.

Question 2

How can this amp deliver 200w (50w+50w+100w) if the power supply only delivers 100w?

Accepted Answer

With the power supply it comes with, it can't.  Most people will be happy with 100w total watts, especially since it can be divided between the channels moment by moment.  That's better than a 25x2+50W amp, since the sub on this could be driven with all the input power, if there was no audio needing the L & R.   However, yes, if you want to get the full power out of this amp, and it has honest ratings, and won't distort or overheat at full output, you'd need to buy at least a 250W PSU (assuming 80% efficiency at full load).   A 24V 10A supply isn't unusual, but will run about $40 if you don't get the absolute cheapest one out there.

Question 3

Can i use an a/b switch at the input to switch between a cd player,and,a turntable?

Accepted Answer

Yes you can !!!!! But you will need a pre amplifier for the turntable if it a mag. cartage !!!!!

Question 4

if I turn up the master volume does the sub volume increase with it, or do I need to adjust the bass volume to not be drowned out by speakers

Accepted Answer

The Master volume controls ALL the channels, including the subwoofer. The BASS VOL  volune knob adjusts the subwoofer volume only, so you can set it as desired relative to the main L & R channels, along with the FREQ knob, which adjusts the subwoofer hi-frequency cutoff.  Once you’ve got the proper balance set, then you use the Master volume to adjust the overall listening level.  The TREBLE and BASS knobs adjust these frequencies for ALL channels, according to you preference.

ASIN	B077QPTPVW
Audio Output Mode	Stereo
Audio Output Type	Speakers
Best Sellers Rank	#158,338 in Electronics ( See Top 100 in Electronics ) #966 in Audio Component Amplifiers
Brand	Fosi Audio
Color	Black
Compatible Devices	Smartphone, Speaker
Connectivity Technology	Bluetooth, USB
Connector Type	RCA
Control Method	Touch
Controller Type	Android
Customer Reviews	4.5 out of 5 stars 924 Reviews
Format	WAV, WMA
Item Weight	2.3 pounds
Manufacturer	Fosi Audio
Mfr Part Number	BL20C
Model Number	BL20C
Number of Channels	2
Number of Items	1
Other Special Features of the Product	Volume Control
Output Power	320 watts
Output Wattage	320 watts
Software Update Supported to Date	unknown
Special Feature	Volume Control
Surround Sound Channel Configuration	2.1 Channel
Unit Count	1 Count
Warranty Description	24-month manufacturer
Wattage	320 watts
Wireless Technology	Bluetooth

BL20C

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