The Fosi BT20A Pro: Review – Fosi Audio
The Fosi BT20A Pro: Review - Fosi Audio
The Fosi BT20A Pro: Review

What a time to be alive.

Pros:

Small

Powerful

Tasteful Colour Options

Tone Controls

 

Cons:
Pre Out instead of Line Out

No input switch

 

Here is Fosi's top of the line stereo Bluetooth speaker amplifier.

 

The BT20A Pro.

When purchasing you have the option to pick between the 32Volt and 48Volt power brick.

I will be reviewing this unit with the 32Volt power supply.

 

Unboxing Photos

Build & Aesthetics

The build quality and finish is exactly what I have come to expect from Fosi Audio.

At this price point there is nothing to complain about.

The blue finish on the body, faceplate and knobs are perfectly matched, and the combination with the orange accent on the volume control is a very welcome change from the monotonous endless stacks of blacks and greys and various aluminium finishes.


2The tone knobs feel robust and don't have any slack but when turning the knobs, the action feels a touch grainy.

The volume knob is easier to turn and has a bit of slack, but the turning action feels buttery smooth and high quality.

The volume knob also doubles as a button for clearing the bluetooth pairing. It has a very short actuation and nice tactile action.

The power toggle switch is a very nice touch.

I'm a very big fan of thoughtfully implemented analogue controls and the ergonomics and feeling of human-interaction with this unit is overall very satisfying.

If however it was any smaller I think I might have problems turning a knob without accidentally touching another knob and changing its settings.

Perhaps someone with larger hands might have more problems touching multiple knobs at

The power toggle switch is a very nice touch.

I'm a very big fan of thoughtfully implemented analogue controls and the ergonomics and feeling of human-interaction with this unit is overall very satisfying.

If however it was any smaller I think I might have problems turning a knob without accidentally touching another knob and changing its settings.

Perhaps someone with larger hands might have more problems touching multiple knobs at once.

The bottom of the unit also has 4 thick rubber feet, and on the rear there are the usual RCA inputs, a Pre Out, the output to passive speakers, the Bluetooth antenna and the power input.

Features & Functionality

 

I found that the most important aspect of this unit for my every day use was the tone control.

I have been using the BT20A with my vintage Yamaha NS-615B speakers; for anyone not familiar with this model, it is the home, consumer version of the legendary and infamous NS-10M studio monitor speaker.

From memory I think the 615B actually sounds a little bit different to the 10M, which I thought had quite hot treble. My 615B is actually quite balanced, if a bit mid-range focused, so I gave them a healthy little boost in both the treble and bass; although any necessary corrections also depend on the speakers distance from the listener, the size of the room and the position of the speakers in the room, not to mention the recording quality and your own music preference.

In the end, what counts is that this feature is not only available, but does a good job of adjusting the tuning in a tasteful and balanced way.

 

Honestly I don't think I've heard my speakers sound this good, but I was also not doing them any justice with my latest previous amp which was the desk-space saving Loxjie A10.

I can't consider that a serious amplifier in the current hifi climate with it's weaker output and significant humming problems on higher volumes, and it feels wrong even mentioning it in this review where it is bested in every possible way by the BT20A.

 

With that pointless little comparison over, I want to move onto the Bluetooth.

At any volume there was no audible humming, and objectively I was extremely satisfied with the quality of the audio signal.

I don't know exactly what the Bluetooth range is supposed to be, but moving my phone all over my apartment never resulted in a staggered or dropped signal; so more plus points there.

One interesting feature is that after you turn the amp off and on again, it will try to automatically connect to the previously connected device.

So if you do not clear the pairing by holding down the power button for 5 seconds, you might wonder why you're not getting any audio from your PC or analogue music streaming device, but in reality the amplifier's Bluetooth connection takes priority over the RCA input.

 

There is no way to switch between input sources, so in that case, you must either turn your the Bluetooth off on your mobile phone or DAP, or clear the pairing by holding down the volume button for 5 seconds.

 

The Pre Out might be useful as an output for some powered sub-woofers, but my vintage powered Yamaha NS-W1 subwoofer requires a much stronger Line Out signal and struggles to reach equal loudness with the speakers on full volume.

 

Sound

 

This isn't my first experience with D-class speaker amplifiers and this certainly does not disappoint.

Beyond that it actually impresses.

Even compared with entry level A class receiver amps, I actually prefer the cleaner and more honest sound of this type of amplifier.

 

As it's musical performance goes, dynamics and detail are noticeably impressive and shine against it's completely black background.

 

It's probably a good thing I'm not trying to power some larger speakers with this, as I do not have the 48 volt power supply, but the 32 Volt brick already gives this amp way more headroom than I'll ever need with my old Yamaha’s.

The BT20A is rated at 300 Watts into 4 ohms, so the 8 ohm NS-615B's should be getting a very healthy 100 or so watts, depending on the output powers relation to the power supply, and they are EASILY being driven close to their full potential.

At no point did I feel like these speakers were being underpowered or lacked control.

 

 

Conclusions

 

In the past I've dabbled with a bunch of vintage receiver amps and a small handful of modern d-class amps; the reality is that D-class technology is now at the level where anyone should be content or even satisfied with the sound quality and features of these little beasts.

 

I can't find any reason not to recommend this amplifier at this price point.

I really like it, and with this product segment being fuller than ever with various options, I don't know why anyone would go want to go with another unit without good tone controls, or some actual modern style.

What a time to be alive where we can get this level of sound quality, power and functionality for this kind of money.

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