Headphone amps in Denon AVReceivers

[ironhorse128]

Recently I have been forced to use the headphone amp of my Denon x2500h for almost all my movie and TV show watching. I mainly use my Argon Modhouse Mk3 which I find are actually quite enjoyable.

• I was wondering if anything is known about the quality of the headphone amp in Denon AVReceivers
• Is there a way to apply EQ to the headphone output
• Can I add headphone amp even though the x2500h does not have preouts. Would preouts really help?
• Any tips on how to improve the experience.

Thanks for your feedback.

 

[MZKM]

If I'm not mistaken, they just use the DAC output, like for Zone 2 pre-outs. The issue, as seen with the knock-off Topping that Amir just reviewed, is that the output impedance is super high, I'll just paste Amir's comments:

"Ah, the truth comes out! Someone just tapped the RCA outs and brought it to the front and called it done. This is wrong as the RCA out typically has high impedance in the order of 100 ohm we see here. That high impedance causes a ton of power loss as we see in the 33 ohm test. And rules out using vast majority of headphones out there as it will interact with their impedance and change their frequency response (tonality)."

I doubt you can apply EQ.

I think you can use the Zone 2 preouts and send that to a HP amp

 

[escape2]

I can only offer up my experience with headphone out in my S740H. The X2500H may be different.
I've watched a few movies with my Philips X2HR plugged into the S740H headphone-out and enjoyed the experience. Definitely loud enough, but X2HR have fairly low impedance (30 Ohm), so they're pretty easy to drive.

No full EQ control for headphones, but you do have basic bass/treble controls.

 

[dkfan9]

Headphone outputs come through a 470 ohm resistor tapped off the left and right speaker outputs.

 

[ironhorse128]

Thanks for the input so far.

 

[Weeb Labs]

Headphone outputs come through a 470 ohm resistor tapped off the left and right speaker outputs.

This is correct. See R6691 and R6692 in the schematic below.

The MCU disables EQ functions when headphones are detected between pins 4 and 5. If you wish to use EQ in conjunction with headphones, you will need to replicate the voltage divider externally and connect it to the speaker terminals.

 

[ironhorse128]

@Otaku+ and @dkfan9 Thanks for your input. It seems that the headphone output is really substandard in these denon receivers.
Yesterday I hooked up one of my RME Adi DACs directly to the TV via optical (bypassing the denon altogether) and this sounded immediately better. The RME Adi DAC gives me loudness and custom EQ options. I guess I will leave it connected to the TV.

 

[Dakotaman]

If I'm not mistaken, they just use the DAC output, like for Zone 2 pre-outs. The issue, as seen with the knock-off Topping that Amir just reviewed, is that the output impedance is super high, I'll just paste Amir's comments:

"Ah, the truth comes out! Someone just tapped the RCA outs and brought it to the front and called it done. This is wrong as the RCA out typically has high impedance in the order of 100 ohm we see here. That high impedance causes a ton of power loss as we see in the 33 ohm test. And rules out using vast majority of headphones out there as it will interact with their impedance and change their frequency response (tonality)."

I doubt you can apply EQ.

I think you can use the Zone 2 preouts and send that to a HP amp

Hi; I am a newbie to high end audio and I have a question. I have a Denon AVR-2500h receiver and I just purchased a high end Focal Celestee Headphone with a impedance of 35 ohms and a maximum input power of 50mW. Given the discussion here regarding the headphone jacks on Denon AVR receivers, I am wondering if I could possibly overdrive my headphones by turning up the volume to high and damage them? I don't know the Maximum output power of the Denon AVR-2500h headphone jack. If so should I possibly get a headphone Amp or a headphone stack like the Magnius + Modius Balanced Amp DAC Stack.

Thanks,

Dakotaman

 

[MZKM]

Hi; I am a newbie to high end audio and I have a question. I have a Denon AVR-2500h receiver and I just purchased a high end Focal Celestee Headphone with a impedance of 35 ohms and a maximum input power of 50mW. Given the discussion here regarding the headphone jacks on Denon AVR receivers, I am wondering if I could possibly overdrive my headphones by turning up the volume to high and damage them? I don't know the Maximum output power of the Denon AVR-2500h headphone jack. If so should I possibly get a headphone Amp or a headphone stack like the Magnius + Modius Balanced Amp DAC Stack.

Thanks,

Dakotaman

I mean, start with the volume down and simply turn it up to taste?

 

[Dakotaman]

I mean, start with the volume down and simply turn it up to taste?

Are you saying plug the headphones in and hope for the best?

 

[escape2]

Are you saying plug the headphones in and hope for the best?

Yes.

If you turn the volume too high on ANY amp, there is a risk of damaging what's connected to it. Your Denon is no exception.

 

[Dakotaman]

Since I don't know the Maximum output power of the Denon AVR-2500h headphone jack and according to your comments above "Ah, the truth comes out! Someone just tapped the RCA outs and brought it to the front and called it done. This is wrong as the RCA out typically has high impedance in the order of 100 ohm we see here." would I not be safer to get a headphone Amp or a headphone stack like the Magnius + Modius Balanced Amp DAC Stack to protect my Focal Celestee headphones which cost 900.00$? I am grateful for your help since this is new to to me. I am 80 years old and retired so I spend a lot of time watching tv and listening to music.

 

[KMO]

Ah, the truth comes out! Someone just tapped the RCA outs and brought it to the front and called it done. This is wrong as the RCA out typically has high impedance in the order of 100 ohm we see here.

This is not true of Denon AVRs (unless something has changed) - that's a quote about a different product that MZKM wrongly assumed to be similar to the Denon.

They actually work as per the other descriptions above - they use the main power amplifier for the L+R channels fed through a 400-ohm series resistor.

This doesn't change the answer that any amp could damage headphones or speakers with too much volume.

Trying to protect your headphones or speakers by limiting your amplifier power doesn't work. If the amplifier runs out of power when you turn the volume up, it clips, producing a distorted signal that could do more damage.

The only way to protect is to limit gain - don't turn the volume up too much or have a device with limited volume.

I don't actually know whether or how much Denon AVRs choose to limit their volume when the headphones are plugged in. (They do know they're plugged in and reconfigure themselves, so they certainly could limit it). Without limiting, I believe that power amp + series resistor circuit would still be able to produce far more power than any headphone could handle, so I assume they do at least some software pre-amp gain limiting too.

The reason to go for a separate headphone amp would mainly be quality. The series resistor to the speaker output is something of a bodge. Might actually work better in frequency response for a low-impedance headphone like yours, but wouldn't compare to a dedicated headphone amp.

There would be some ease-of-use differences too, I guess. The headphone socket on an AVR is auto-sensing, and disables the main zone output, so you have to connect and disconnect the 1/4" plug to switch between headphone and speakers. With a headphone amp, you could permanently connect to the Zone 2 pre-outs, and just turn main zone (speakers) and zone 2 (headphones) on and off via the remotes, and use both simultaneously.

Oh, and you would be able to set a volume limit on Zone 2 in the AVR - exactly what you would want to make headphone damage impossible.

 

[Dakotaman]

Thank you KMO.