Using speaker amps for headphones

I wanted to start a thread to see if there were others who have been using speaker amps with headphones. Currently I’m using my Hegel H80 for my Susvara but it’s too noisy for my more sensitive headphones. I’ve been the search for a quieter amp to pair with more headphones. Has anyone tried using speaker amps? If so, which ones?

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I’ve used my FX-Audio Tube-P1, a massive 2 W per channel, with my DEVA and AKG K51 headphones and it does a very nice job with them.

Mark Gosdin

I’ve used a variety of speaker amplifiers to drive “more demanding” headphones (a very small number of very inefficient models, such as the HE6, Susvara and Abyss) to good effect.

However, there are more downsides than benefits for headphones that have more reasonable sensitivity ratings (and even the Abyss doesn’t benefit much vs. some of the more potent dedicated headphone amplifiers).

You’re at much higher risk of a power on/off transient (or “pop”) outright destroying your headphones. Same with forgetting to zero the volume before starting playback.

Then, as the impedance of the headphones goes up, the smaller the “benefit” of having speaker-amp power levels becomes. For example, at 50 ohms a 50w power amplifier would give you just double the power in to the HE6 that a Jotunheim 2 would yield. Use a 300 ohm headphone, and that drops to only 0.1w more than the Jotunheim 2 would deliver.

Even when you do have a much bigger power margin, the headphones will only draw so much, and once you’re past the point where the amplifier is still its sweet spot in terms of load/performance while giving you, say, 100% headroom on the power they can draw, there’s nothing to be gained from having more power available.

Then there’s the noise issue you’ve run into. That’s going to be a factor with the vast majority of speaker amplifiers. Unless you get can the manufacturer’s noise VOLTAGE level ratings (usually expressed in millivolts, with a few super-quiet models being in microvolts), it’s a crap shoot. Particularly when you consider that an amplifier that had 10mV of residual noise would result in hiss at 76 dB in something like Focal’s Clears or and LCD-4z.


So, notwithstanding that its not a particularly good way to drive normal-sensitivity headphones as a “just because”, I’ve tried it with most of the speaker amplifiers I’ve had in my hands recently.

The Chord Étude, Linn AK2200/AK4200 and Benchmark AHB2 were quiet enough to not yield audible noise with my general array of headphones. The Anthem, Classé, McIntosh* and others all had too much hiss for the job at hand with anything shy of the HE6, Susvara and Abyss.


*I’m referring to their actual speaker amplifiers, not the MHA100/150/200.

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I do understand that more sensitive headphones won’t make a whole lot of sense with speaker amps but it is a pain to have to spend a good deal on a headphone amp that only powers headphones while I have speakers on my desk as well. I was hoping to consolidate my amplification since it seems to make more sense to spend money on good amplification rather than spread my money around to multiple amps.

I do feel like with harder to drive headphones, the power supply plays a bigger part than just the specs. Based on specs, Jot 2 is literally all you ever need. However, I think we can both agree that there are much better amps than the Jot 2. I think people have found a good amount of success using a J2 or XA25 with the HE6 or Susvara. Since I’ve been heading down that road, if I can stick with one amp, then that’s what I would prefer.

I’ve seen other people have success with the AHB2 as well but I’m just a little hesitant with that one due to Benchmark’s signature of being extremely clean and transparent. I’ll have to look into the other ones you mentioned though. I’ve been flip flopping between class A or not since my speakers do require a good amount of juice.

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The power supply does make a difference, for sure. That’s true with almost all audio electronics. But it’s a somewhat moot point if to get a sufficiently stiff, stable and quiet PSU you’re saddled with a gain/power stage in the amplifier that yields clearly audible noise even with the volume turned down.

Which isn’t to say it isn’t worth it, just that it’s a very small number of speaker amplifiers that are going to be quiet enough to be usable with the bulk of “normal” sensitivity headphones out there.

I picked the Jotunheim 2 as a reference simply because it’s an inexpensive, quiet, and powerful option (and I didn’t have to look up the specs).

My mentioning the AHB2 should not be taken as a recommendation - it’s not an amplifier I would personally want to use for long term musical enjoyment. But it was quiet enough to work with normal headphones.

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I bought the adapter from ampsandsound to play my 2 channel with my ZMFs and was interested n hearing how my Audio Research Ref75 amp soundsbut it did not sound that great. The noisefloor was through the roof too.

I’ll try it again with my golden tube audio amp and once I build my pass labs amp camp amp and first watt F6 diy builds I’ll try those too.

I should also try a headphone that has a really low impedance too. Zmfs might not be working well with this idea.

@driftingbunnies you already know my experience with XA25, but maybe others will find my experience of further interest. Susvara really opens up with speaker amp as does my LCD-4. This compared to V281 I previously had and HPA-1 I have now and the P-750u I recently bought from you. My first use of speaker amp with HPs was with my X150.5, but as you mentioned noise was an issue with more sensitive headphones. X150.5 has 200uv of noise. XA25 is less than 50uv. I think J2 is 100uv. With no music playing, I can still hear a tiny bit of hum/buzz, but not noticeable with anything playing. I built this speaker amp setup (also using Pass XP-12 pre) with the Susvara specifically in mind and will probably just use the HPA-1 or P-750u for my less sensitive headphones.

Just to question here, are you all (I know @Torq is) talking about using the actual speaker output of an amplifier to drive headphones? Like maybe wiring a female headphone jack to the binding posts?

Or are you talking about using a headphone output in a receiver, integrated amp, or pre-amp to drive headphones? If the former, what protection and/or attenuation are you using? If the latter, that’s a different story entirely.

I don’t think I’d try to run headphones directly off of even my 70w RMS per channel Onkyo, much less the Sansui, or my Wired 4 Sound STI 1000.

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I’ll point out you need to be careful with Tube based speaker amps, they are designed to drive a specific impedance, and you’d want to match that with either a resistor in parallel with the headphones or a transformer to impedance match.
It’s also the case that more powerful tube speaker amps will self destruct/blow a fuse if a load is not connected to the terminals, because without the reflected impedance the circuit will draw too much current.
Most SS amps won’t care about the load but you’ll be voltage limited into higher impedance’s, so you’ll end up with a lot less power than what’s written on the box, often less than some more powerful headphone amps.

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As I mentioned in my post, I’m talking about an XA25 speaker amp fronted by an XP-12 preamp. I use a custom adapter that goes from spades to XLR female. The Susvara is particularly inefficient for aheadphone (83db/mw, 60ohm) and is particularly power hungry. Using a speaker amp provides performance that is so clearly superior (IMO) to what I have experienced with conventional headphone amps. To be clear, I am not advocating this for typical conventionally or very sensitive HPs.

As @Polygonhell mentioned, power is reduced at higher impedances. A solid state amp at 8 ohms will probably only have about 1/8 of it’s power at 64 ohms. So a 25W amp at 8 ohms will only have about 3W at 64 ohms. So it’s not as extreme as you might have thought.

Although I wouldn’t go so far as to say that headphone amps “often” are more powerful. My XA25 is actually measured at 80W into 8 ohms per Stereophile. That would work out to 10W at 64 ohms. I can’t think offhand of a headphone amplifier that can produce that much power into 64 ohms.

The Bakoon 13R is effectively a speaker amp that can also drive it’s full output out of it’s headphone jack.

I also agree that for a OTC tube amp, you can’t use a high impedance headphone without something like a parallel resistor. Second picture below is an example of what I did with my Primaluna Prologue tube amp to provide a parallel resistance for the amp close to the expected 8 ohms.

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Here is a rather cheap and foolproof experiment. Buy an Emotiva BasXa-100 amp for $229.00. It has both a headphone socket and a speaker tap. They have a 30-day return policy so if the experiment does not produce the results that you want, then you can return it with only the cost of shipping. Read the reviews on the Emotiva site or do a Google search.

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Also, connecting HPs to speaker amps is not a completely unprecedented idea. HifiMan sells an adapter just for this purpose. It does include resistors in series and in parallel although some have noted that it does introduce a veil compared directly connecting to the speaker amp.

https://www.hifiman.com/products/detail/84

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Fyi I have used the speaker taps of Mogwai SE (with input transformers) and the Maraschino STM speaker amp from Cherry Amps to drive a pair of Susvaras with good results. No audible noise or hiss.

(I did try it with the Hifiman adapter first, however didn’t care for the effect on the sound)

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How did your amps deal with other headphones off the speaker taps? Any hiss with the Cherry Amps? It seems like less and less manufacturers are reporting a noise output number so it’s difficult to know which amp will work with more sensitive headphones.

I was thinking and wondering about this question today… So far, I haven’t tried other headphones from the speaker outputs because

  1. The Mogwai provides multiple headphone outputs for different impedance loads, and is a really good (and very powerful) source for many headphones which greatly reduced the need (temptation? :-)) for me to try the speaker taps with other headphones

  2. The headphones in question would need balanced cables, which narrows the choices

I may still have balanced cables for a couple of pair of more sensitive headphones that I haven’t been using much (since I got the Susvaras) that I could try. I’ll check that out and if so, will give them a try and let you know how it goes.

I’ve got a couple of other things I need to work on (sometime life gets in the way of the hobby :wink:), I’ll try to get back to you by the weekend.

Not a speaker amp directly but I was wondering if folks here have experience running the Susvara off the taps on the back of the Hugo TT2 vs dedicated speaker amps (or eg speaker taps on the Mogwai SE).

Yes, I tried, some of the amplifiers sensitive and noisy.

In summary, I don’t detect any hum or hiss when listening from the speaker outputs of either the Mogwai SE or Maraschino STM amp with either Audeze LCD-X or Hifiman HE-560.

Of course, LOTs of source volume attenuation is needed (at the source and/or at the DAC/preamp stage) to get the signal levels down to suitable levels.

Happy listening, whatever you decide.

So currently I’m using the Pass Labs Int-25 and there’s some noise but once I turn the volume up a little, it’s not as noticeable even though it’s there. I’m guessing the best will be an integrated amp or pre with headphone out but once you get higher up, there aren’t a lot that include that feature.

However, I will say that the sound is pretty great. I should be receiving my Sus back on Wednesday so I’ll be able to see if it was worth the effort since so many others have said that Pass really works well with it.

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Two highly regarded items, for sure, hopefully will be great together :-). Let us know what you think.

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