Topping PA5 II Stereo Amplifier Review

[restorer-john]

I'll see if I can find my thermocouple and measure my wife's the next time she leaves it in overnight. It's definitely quite warm to the touch.

I think you might have to rewrite that....

 

[jmillar]

With no EQ, setup A sounded like if my speakers didn’t have woofers. Setup B, with no EQ sounded immediately more balanced. I then tried to adjust EQ (on setup A) and loudness/bass/treble (on setup B) to try to get the best sound out of both.

Setup A is able to play louder than setup B but it lacks something in the bass department. No combination of EQ compensates for this lacking of fullness in the low frequencies. I could get the lowest frequencies to be there but it’s like there was weak spots in the low frequency bands. Tried both parametric EQ and discrete frequencies EQ. No luck. No setting would give me the balanced full sound of the setup B. I also noticed that pushing frequencies way above zero on the parametric EQ resulted in having the audio compressed when played at high levels but I guess this is the way WiiM deals with avoiding distortion. To avoid this I EQed only below zero.

For curiosity purposes I also tested the WiiM with no EQ connected to the line-in of the Sonos Amp. Still no joy. The sound still lacks something in the lower frequencies.

Unfortunately I didn’t have a way to get a line level signal from the Sonos Amp to inject in the Topping PA5 II so I tested lossless Apple Music Air Play > LG TV > Topping PA5. Awful sound with audible distortion (even controlling the level out from the TV to a level comparable to the WiiM line out). I then tested the same thing but connected to the Sonos. I’d say it was slight better but still bad.

I’ve decided to return setup A (still on the 14 day period) as it has inferior quality (to my ears) compared to my old Sonos Amp.
My Sonos Amp was sometimes exhibiting interruptions of audio when streaming and it was slow responding to requests from the app so a bit painful to use. However, I’ve discovered that it was possible to downgrade the firmware from S2 to S1 and so I did it. It is now much faster with no interrupted audio. Happy

All this is to say that I’m disappointed with the performance of setup A despite the very good reviews they both have.
How can the Sonos sound so much better to my ears than setup A? I feel we are not measuring everything that matters in this tests. I know this testimonial of mine is very subjective but when I see the frequency response in @amirm tests and compare it with what I heard.. it just doesn’t match. Is it maybe dynamics? The time a certain frequency response takes to achieve a certain power level?

Sonos gear has built in "loudness compensation". That's a possible reason for those A/B results.

 

[Yorkshire Mouth]

If I'm just wanting to use this as a power amp, I note there's no switch to disable volume.

Should we just be turning it up to full? Will this just turn it to full, or if you wind it right round do you effectively disable volume (turn it 'off') bypassing the volume circuitry?

Many thanks.

 

[staticV3]

If I'm just wanting to use this as a power amp, I note there's no switch to disable volume.

Should we just be turning it up to full? Will this just turn it to full, or if you wind it right round do you effectively disable volume (turn it 'off') bypassing the volume circuitry?

Many thanks.

The volume circuitry cannot be bypassed.
When turning volume to full, you set the attenuation to zero.

 

[Yorkshire Mouth]

The volume circuitry cannot be bypassed.
When turning volume to full, you set the attenuation to zero.

Presumably that's the best/correct option if using as a power amp?

 

[staticV3]

Presumably that's the best/correct option if using as a power amp?

I usually recommend setting your source to full volume, then attenuating the Amp accordingly.
That generally results in the highest SNR.

 

[Guddu]

I usually recommend setting your source to full volume, then attenuating the Amp accordingly.
That generally results in the highest SNR.

+ it also may prevent an accidental high volume situation.

 

[Yorkshire Mouth]

I usually recommend setting your source to full volume, then attenuating the Amp accordingly.
That generally results in the highest SNR.

A problem if you're pairing this with (say) a WiiM Ultra and using the sub out, as you need one volume control to set the volume on both main L&Rs and the sub.

Using the PA5's volume control would adjust the main speakers' volume, but the sub would remain the same.

 

[Yorkshire Mouth]

+ it also may prevent an accidental high volume situation.

Would that be any more or less of a risk than if this were a pure power amp with no volume control?

I can't see the difference.

 

[Sokel]

Would that be any more or less of a risk than if this were a pure power amp with no volume control?

I can't see the difference.

The difference is that the source is already at max level,there's no risk as it it was at -40db for example and a (rare) glitch skyrocketed it to 0db.
In such case (source at max) either a pre-amp or some other VC scheme is used with a normal power amp with no VC.

In the case that the VC is digitally controlled by the source straight to a normal power amp some other fail-safe structure must be used,a voltage divider for example (with care not to mismatch impedance) to the loudest level one prefers (including peaks and well within the speaker's ability)) but no more.

 

[Julf]

Would that be any more or less of a risk than if this were a pure power amp with no volume control?

A "pure" power amp with no volume control is always at full gain, whereas if the amp has volume/gain set to a lower setting, the maximum power you get if you turn up volume to full in the source is lower.

 

[Guddu]

Would that be any more or less of a risk than if this were a pure power amp with no volume control?

I can't see the difference.

Although useful & great information has already been added by members in their replies, I am just adding or summarizing a few:

- an amplifier is always running to its gain settings, i.e., it is always running to its configured potential
- amplifiers with volume control or knob or potentiometer are no different from amplification point of view, they amplify just like another power amplifier however the input is controlled to put it simply
- this potentiometer controlling input (or volume, simply) in amplifier can potentially cause a few issues like additional noise, channel imbalance, etc. in case if the components used aren't of decent standard as we have seen a few times in different reviews or measurements. This makes a case to keep potentiometer to its highest position to minimize any undesired impact, if needed or if there is any
- Lastly, in many case, for safety & ease, controlling volume on pre-map/DAC makes more sense than amplifier.