Topping L30 II Review (Headphone Amp)

[Contrario]

I have an Audient ID14 MKII audio interface that I've been mainly using with my Sennheiser HD 600 headphones. I've decided buying a Topping L30 II to be able to drive my headphones better. I always use oratory1990's 2018 Over-Ear Harman target EQ settings and it reduces the output level -9.3 dBFS. I've thought having a proper headphone amp that could drive my 300 ohm headphones would give me more sound pressure level and headroom.

According to the measurements of Julian Krause, Audient ID14 MKII's headphone out provides 75.50 mW when connected to a Type-C port and only 11.80 mW when connected to a USB 3.0 port. That’s because it runs at 1500 mA through USB Type-C and 900 mA through USB 3.0. I have my PC having several USB Type-C ports but I sometimes happen to have to use the USB 3.0 ports of the computers I have in different locations.

I received the L30 II yesterday and tried it first with a dirt cheap 3.5 mm TRS -> 2 RCA cable and onboard line/headphone out of the computer I use now. I noticed the sound pressure level was not much different at high gain and max volume from my interface’s headphone out at unity. I found that very strange because I had read many comments about how the L30 II was more than powerful enough to drive Sennheiser HD 600 and 300 ohm headphones in general. That forced me to do some research and discover that L30 II must be fed 2 vRMS to be able to meet the specs, which is 560 mW into 300 ohm. That is more than what Hd 600 requires, which is 200 mW.

Upon that, I’ve measured the line and headphone outs of my interface connected through USB 3.0 with the same 3.5 mm TRS -> 2 RCA cable and a multimeter while 0 dBFS 60 Hz tone was constantly playing. Here are my measurements:

Line Out with -9.3 dBFS gain reduction at unity: 1.66 vRMS
Line Out without any gain reduction at unity: 3.09 vRMS

Headphone Out with -9.3 dBFS gain reduction at unity: 3.28 vRMS
Headphone Out without any gain reduction at unity: 3.83 vRMS

I haven’t purchased the TS -> RCA cables yet to connect the L30 II through the line outs of my interface because I have some doubts about several things. I seek your help on them.

I just want to be able to listen to, record and mix music while using my HD 600, ATH-M50x and KZ AS10 at levels between 85-100 dB SPL while using the Harman target EQ. Is the L30 II really needed for that purpose?

Would feeding the L30 II with 1.66 vRMS be enough? If not, could lowering the -9.3 dBFS reduction work?

What about using the headphone out of my interface? Would this lower the quality?

Could the balanced TRS outs of my interface be a problem for the unbalanced inputs of the L30 II? Can I just use unbalanced TS -> RCA cables?

I know the impedance, efficiency and sensitivity values of my headphones and I can use a multimeter to measure voltage but I still don’t know how to calculate loudness with the given values. Can you also help me with that?

 

[DeDovla]

I know the impedance, efficiency and sensitivity values of my headphones and I can use a multimeter to measure voltage but I still don’t know how to calculate the loudness with the given values. Can you also help me with that?

I usually use this power calculator as you can input all the data you have:

https://support.beyerdynamic.com/hc/en-us/articles/360021705639-Will-my-headphones-be-loud-enough-on-my-amplifier-Online-calculator

L30 II output impedance is between 0-1Ohm (closer to zero so I use 0.1 Ohm personally). Other data you already have, so you can easily use it and it will give you how much dBSPL and power (in mW) you get.

A basic formula to calculate power is I = V*V/R where V is the output voltage and R is the resistance and I is the power in watts (for example if you get 0.1W as a result that is 100mW), but for dBSPL you should just use this calculator as it's way less hassle.

 

[staticV3]

I just want to be able to listen to, record and mix music while using my HD 600, ATH-M50x and KZ AS10 at levels between 85-100 dB SPL while using the Harman target EQ. Is the L30 II really needed for that purpose?

No.

Would feeding the L30 II with 1.66 vRMS be enough?

Feeding the L30II with 1.66Vrms would be enough to drive the HD600 to 125dB SPL Peak.
That would likely destroy your headphones and your hearing.

What about using the headphone out of my interface? Would this lower the quality?

No.

Could the balanced TRS outs of my interface be a problem for the unbalanced inputs of the L30 II?

It's possible. Audient will know more.

Can I just use unbalanced TS -> RCA cables?

Probably. Audient will know more.

I know the impedance, efficiency and sensitivity values of my headphones and I can use a multimeter to measure voltage but I still don’t know how to calculate the loudness with the given values. Can you also help me with that?

Any specific questions or examples?

 

[Ahmonge]

Could the balanced TRS outs of my interface be a problem for the unbalanced inputs of the L30 II? Can I just use unbalanced TS -> RCA cables?

I don’t think is a good idea to connect a balanced line output to an unbalanced line input. They are other HP amps with balanced inputs that won’t cause connection problems at all. Talking about using a TS jack on a TRS socket, this will short the R (cold) and S (shield) outputs of your interface line outputs which is a bad idea if the output is actively balanced. In this case, a TRS jack with the S left unconnected would be the way to go.

https://community.avid.com/forums/t/58612.aspx#:~:text=Balanced%20connections%20have%20three%20signal,more%20on%20this%20to%20follow).

 

[DeDovla]

According to the measurements of Julian Krause, Audient ID14 MKII's headphone out provides 75.50 mW when connected to a Type-C port and only 11.80 mW when connected to a USB 3.0 port. That’s because it runs at 1500 mA through USB Type-C and 900 mA through USB 3.0. I have my PC having several USB Type-C ports but I sometimes happen to have to use the USB 3.0 ports of the computers I have in different locations.

Also, forgot to mention about this -> when using a USB 3.0 port they state that the device can output 11.80mW into 300Ohm headphones which is actually 2V because the headphone output impedance is around 20Ohms (EDIT: 22 Ohms to be exact but it shouldn't matter much for your calculations). At max volume it should drive your headphones to 109-110dBSPL. When using Type C the output voltage is around 4.8V which would obviously be even louder (EDIT: plugged the numbers into the calculator the voltage is between 5V and 5.1V it seems due to output impedance of 22 Ohms eating into it a bit).

The only difference in sound quality could come from output impedance as the SINAD of the DAC inside it is near 100dB which is usually fine for most cases. However since impedance of the headphone is 300Ohm it is more than the rule of 1/8 (EDIT: 22Ohm output impedance should only affect headphones of impedances of up to 176 Ohms with a non-flat impedance curve, and those above 176Ohms should not be affected) so it should not affect the HD600 and if it somehow does you will get ever so slightly more warmth/bass (probably not noticeable).

 

[Contrario]

This forum rocks. Many thanks to @DeDovla, @staticV3, @Ahmonge for teaching new things and erasing every question mark in my mind.

 

[Contrario]

I don’t think is a good idea to connect a balanced line output to an unbalanced line input. They are other HP amps with balanced inputs that won’t cause connection problems at all. Talking about using a TS jack on a TRS socket, this will short the R (cold) and S (shield) outputs of your interface line outputs which is a bad idea if the output is actively balanced. In this case, a TRS jack with the S left unconnected would be the way to go.

I got in contact with Audient. Here is their response on the matter:

 

[Ahmonge]

I got in contact with Audient. Here is their response on the matter:

Great! Good customer support.

 

[nagster]

I got in contact with Audient. Here is their response on the matter:

According to the support response and the manual, it seems to be an impedance balanced output.
In that case, no abnormalities will occur even if the cold output is open or shorted to ground. The output circuit will also not be damaged. The disadvantage is that there is no CMR.

https://d9w4fhj63j193.cloudfront.net/2021/iD14MKII/English/iD14%20MKII%20Manual%20V1.3.pdf

 

[xaon60]

Question: Is there any risk in running the D90SE at 5V (2.6V RCA) to power the L30II?

 

[Contrario]

Question: Is there any risk in running the D90SE at 5V (2.6V RCA) to power the L30II?

The input sensitivity of L30 II is 2 Vrms. It starts to clip when you feed it higher than that. You can try to lower the volume on your computer when using the RCA outs of the D90SE until a DMM reads 2 Vrms during a 60 Hz sine wave is constantly playing at 0 dBFS.

 

[xaon60]

The input sensitivity of L30 II is 2 Vrms. It starts to clip when you feed it higher than that. You can try to lower the volume on your computer when using the RCA outs of the D90SE until a DMM reads 2 Vrms during a 60 Hz sine wave is constantly playing at 0 dBFS.

Sure, thanks for the clarification. : )

 

[staticV3]

The input sensitivity of L30 II is 2 Vrms. It starts to clip when you feed it higher than that.

Only with volume set to max.

Reduce the gain and/or reduce the volume knob volume and you can input higher voltages.

 

[Contrario]

Only with volume set to max.

Reduce the gain and/or reduce the volume knob volume and you can input higher voltages.

The L30 II was clipping at medium volume at high gain when I fed it 3 Vrms through the headphone output of my Audient ID14 MKII.

 

[xaon60]

I left the D90SE at the default settings. I use Roon's parametric equalizer with Amirm settings for my K701, and I am at medium gain.

 

[Contrario]

Then it might have been my audio interface's headphone output that was clipping.

 

[xaon60]

I don't know if it's because of the proximity of my phone, but I just heard a faint interference noise in my K701. It seems to be random; I received another message and it didn't happen.

 

[solderdude]

Quick and dirty test:
Put your phone on top of the cable(s) or DAC and call that phone using another phone (do not pick up).
This usually generates a lot of burst type higher power RF which is detected by electronics in the usual sounds (familiar once you hear it).

Note: The RF field-strength generated at such close proximity exceeds that of what devices have to be immune to so don't worry if you hear sounds.
At say 0.5m away the field strength is already drastically lower.

 

[xaon60]

I’m making this remark because I’ve never observed this phenomenon on my equipment, including with headphones connected to the back of the motherboard. It doesn’t worry me; I’m just not used to it.

 

[hutt132]

I don't know if that's why Amir no longer shows the L30II's 50mV SNR result, but his original measurement of >100dB is probably a measurement error as the AP Analyzer is incapable of measuring such low noise values.

You need to use an external LNA to faithfully measure the L30 II's noise output, as the APx555 alone is not good enough:
View attachment 326361

If you do, then >105dB SNR @50mV can be measured, as you can see here: https://www.l7audiolab.com/f/topping-l30ii/

The 50mV chart and the SINAD chart, to me at least, show how Amir's APx555 can no longer keep up with new releases and instead, he's just measuring his analyzer's inherent noise and distortion over and over again.

What would you assume is Amir's analyzers limit for this type of measurement? 95 dB?

EDIT: Just read the note on audio lab:
Due to the limitation of AP's own noise floor (the maximum measurement is about 95), I used an amplifier to amplify the signal and noise (which actually degrades the result) to perform equivalent measurement under 50mv.