# Topping A30Pro Review (Balanced Headphone Amp)

#### staticV3

##### Major Contributor
So even if my DAC only outputs 2 Vrms from RCA I still get 6w at 16ohm from the amp?
2*10^(14/20)=10 so you will get 10Vrms output with 2Vrms input and gain set to +14dB.
10Vrms^2/16Ω=6.25W

#### Electrolite

##### New Member
2*10^(14/20)=10 so you will get 10Vrms output with 2Vrms input and gain set to +14dB.
10Vrms^2/16Ω=6.25W

That's actually scary, looks like my DAC is more than enough....
Can you explain the formula used to calculate the output voltage? What are the numbers here: 2*10^(14/20)=10

#### staticV3

##### Major Contributor
Output voltage = input voltage * 10^(gain[dB]/20)

#### abhishek

##### Member
Hello I'm new to this thread
I have problem of power cutting issue when bass heavy (only one recording discovered) music is played on My new a30 pro on high gain 2oclock knob
My hifiman arya V2 was on full volume on my old topping A50s, no problem here.
Paired with fiio K3 dac 2v 3.5 mm rca line out
Has anyone faced this issue?

Edit: came to know from page 40 that amp going to DC protection mode when recording has DC source ,the silmarillia 2019 recording mix is the music which I listened.

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#### reptilianbrain

##### Member
Do I want A30Pro or A90 for HD800s? The price is roughly the same.
I have 4.4mm balanced cable
I plan to just get D10 balanced to pair with it

#### Rayman30

##### Addicted to Fun and Learning
Forum Donor
Do I want A30Pro or A90 for HD800s? The price is roughly the same.
I have 4.4mm balanced cable
I plan to just get D10 balanced to pair with it

Then get whichever is cheaper, the A90 is truly balanced and does have more power... but honestly that's not going to make any difference.

#### usern

##### Active Member
A30pro and A90 both can drive HD800s extremely loud, possibly to headphone distortion levels. You should consider quirks and features. A30 pro gets hotter than A90, but it's also smaller. If you have a very quiet room you might hear high pitched buzzing sound from A30pro when it's turned off from the front, but switched on from the back. Don't know about noise from A90 since I haven't owned it.

Got the A90

#### microcontrollerpro

##### Member
Would the A30pro be sufficient for driving the HE6SE v2 with eq, or should I get the A90? I would prefer to get the A30pro as I can place it on top of my SMSL SU-9n while the A90 would need to be placed somewhere else.

#### Leiker535

##### Active Member
Would the A30pro be sufficient for driving the HE6SE v2 with eq, or should I get the A90? I would prefer to get the A30pro as I can place it on top of my SMSL SU-9n while the A90 would need to be placed somewhere else.
It will be plenty fine, specially if you input a balanced signal.

#### microcontrollerpro

##### Member
It will be plenty fine, specially if you input a balanced signal.
Thanks for confirming. Will be inputting a balanced signal from the SMSL SU-9n.

#### staticV3

##### Major Contributor
Would the A30pro be sufficient for driving the HE6SE v2 with eq, or should I get the A90?
Here's the max voltage vs load graph for both:

At 65Ω (HE6SE) you're looking at 14.8Vrms for the A30Pro and 16 for the A90.
In terms of perceived loudness the A90 will be ~4.8% louder.

Max SPL with the HE6SE will be 114.7dB with the A30 Pro and 115.3dB with the A90.

Bringing the bass and 1.7KHz dip up to Harman will cost you about 7dB of max SPL:

So with EQ you're left with ~108dB SPL peak with both amps. Should still be sufficiently loud.

#### Prism24

##### Member
Would I be able to run this amp with full output power (excuse my layman terminology ) using the balanced outputs from an E50 DAC with a TRS to XLR cable? Or is the matching D30 pro DAC with XLR cables required for full power?

#### staticV3

##### Major Contributor
Would I be able to run this amp with full output power (excuse my layman terminology ) using the balanced outputs from an E50 DAC with a TRS to XLR cable? Or is the matching D30 pro DAC with XLR cables required for full power?
E50 with TRS to XLR cables will give full power.

#### Prism24

##### Member
E50 with TRS to XLR cables will give full power.
Good to know, thanks!

If I make do using my Fiio K5 Pro solely as a DAC with this amp, how much power am I giving up? And would I want to use the volume knob and gain on the Fiio at all?

#### MattISO

##### Member
2*10^(14/20)=10 so you will get 10Vrms output with 2Vrms input and gain set to +14dB.
10Vrms^2/16Ω=6.25W
I want to use the A30 Pro and a balanced DAC (SMSL SU-8s) with EQ and an IEM. In EQ I'll be using a pre-amp gain of -9dB to avoid clipping, which would result in the DAC outputting ~1.42Vrms to the A30Pro instead of 4Vrms. The IEMs impedance is 22 Ohms. Using these formulas, the output should be:

1.42 * 10 ^ (14/20) = 7.11Vrms output with 1.42Vrms input in High Gain (+14dB)

7.11Vrms ^ 1.42 / 16Ω = ~1.01W at 16Ω

7.11Vrms ^ 1.42 / 22Ω = ~0.736W at 22Ω, for my IEM

Is this correct?

#### staticV3

##### Major Contributor
Is this correct?
The SU-8s via XLR has an output voltage of 4.05Vrms.
With a preamp of -9dB that's 4.05*10^(-9/20)=1.44Vrms.
Amplified by the A30Pro in High gain you get 1.44*10^(14/20)=7.22Vrms.
To calculate power from impedance and voltage, do Vrms^2/Ω:
7.22^2/22=2.37W
->that much power will kill any IEM.

#### MattISO

##### Member
The SU-8s via XLR has an output voltage of 4.05Vrms.
With a preamp of -9dB that's 4.05*10^(-9/20)=1.44Vrms.
Amplified by the A30Pro in High gain you get 1.44*10^(14/20)=7.22Vrms.
To calculate power from impedance and voltage, do Vrms^2/Ω:
7.22^2/22=2.37W
->that much power will kill any IEM.
O OK Thank You very much.

#### abhishek

##### Member
OK, very strange. After further investigating, it only happens with a specific song. And only at a certain volume (about halfway on the knob, medium gain). It shuts off after that point and will keep power cycling itself. If I back the volume down, it will stop power cycling and stay on. Here's a video:

The fact that it's only one specific track that's doing it makes me think it may be a negative reaction to DC offset? My interface is infact DC coupled (Ultralite AVB), so if a source recording does have DC components, they'll make it out of my interface intact. Is the Topping's front end getting overloaded past a certain gain point with DC present? Here's the track in question if anyone wants to play around themselves, it's completely unmodified from CD source material (other than lossless FLAC compression of course). Any DC present was in the source recording: https://fohdeesha.com/data/other/05 - Blue Light (Engineers 'Anti-Gravity' Mix).flac

EDIT: Confirmed that the above track has nearly 4 volts of DC offset, assuming your interface puts out around +20 dBu at 0dbFS. Playing that back through *any* amp is probably not the best idea, and Bloc Party needs to fire their mastering engineer
I too had same DC protection with my a30pro.
I downloaded your flac file and checked the waveform,It looks weird. The FFT graph has infinite low frequency peak and scope graph shows offset from zero.

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#### kwanpeter

##### New Member
Topping engineers, I want to appeal for some features that I have found extremely useful in the single-ended L30. I hope you will create a balanced headphone amp with pre-amp in a similar implementation as the L30, perhaps in the price range of A30pro.

What is special in the L30?

1. The amp can be switched into pre-amp mode or headphone amp mode with a single flip of a switch.

2. In the pre-amp mode, the volume is also controlled by the amp's potentiometer.

3. All the features and volumes are controlled by physical switches and knob.

I understand that Topping has such an implementation in the A90. But I want something more in the price range of A30pro. I will buy such a headphone amp in a heartbeat! Perhaps in a future "A30S Pro"?

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