Pairing a OTL tube amp with low impedance headphones, a bad idea?

[linx]

Hello fellow audiophiles,

I am pretty new to the whole Hi-Fi scene, and I need some help with my next setup upgrade.
I recently started with a very basic setup: HiFiMan HE400SE powered solely by an SMSL SU-1. Although this works (and is a tremendous upgrade over my Logitech gaming headphones), the headphones do not get enough power, I think. Even at full volume settings, the actual volume output is mediocre. Thus, I am looking for a headphone amplifier.

I came across a very good offer for a used La Figaro 339 (~$300). I have been intrigued by tube amps since my high-school physics teacher (a die-hard audiophile) has been making propaganda about them and toroidal transformers. I like listening to rock, classical, and sometimes jazz, which I have read online are genres that benefit from tube amps. This, in addition to the aesthetic of a tube amp, makes me want to buy the mentioned La Figaro 339.

In some forums, I have read that pairing a tube amp with planars (HE400SE has 32 ohms) is a bad idea due to the low damping factor resulting from the amplifier's low output impedance (23 to 43 ohms depending on the tubes used), which then violates the "rule of eight." On the other hand, I have read that some people have successfully paired the HiFiMan HE-500 (38 ohms) with the La Figaro 339.

My first question now is: Is it a dumb idea to pair the La Figaro 339 with the HE400SE?

Further, if I were to upgrade to the La Figaro, a headphone upgrade would be next. I really do like my HE400SE (I have even diy upgraded to a suspended headphone band) and have also been considering some other HiFiMan planars (but then again, the low impedance dilemma sets in) due to them being pretty affordable. I have gone through Amir's headphone review index but can't really find anything that is recommended and within my price range of about ~$500. Can you recommend something (they don't have to be planars, but definitely over-ear and open back )?

 

[DVDdoug]

powered solely by an SMSL SU-1. Although this works (and is a tremendous upgrade over my Logitech gaming headphones), the headphones do not get enough power, I think. Even at full volume settings, the actual volume output is mediocre.

Yeah... I don't think that's a headphone amplifier...

In some forums, I have read that pairing a tube amp with planars (HE400SE has 32 ohms) is a bad idea due to the low damping factor resulting from the amplifier's low output impedance (23 to 43 ohms depending on the tubes used), which then violates the "rule of eight." On the other hand, I have read that some people have successfully paired the HiFiMan HE-500 (38 ohms) with the La Figaro 339.

Can you find the specs on the La Figaro? If it's rated to drive 32-Ohm headphones it should be OK. If you can't find the specs, I wouldn't take a chance.

I wouldn't generalize too much about tube amps (or any particular technology). There are tube amps that can drive 4 or 8-Ohm speakers (but they usually have output transformers).

I believe planars tend to have fairly constant ("flat") impedance over the frequency spectrum which means the frequency response won't get as messed-up with a higher impedance amp so it might be OK as long as it has enough output voltage (with the low impedance load) to go loud enough.

Personally, I avoid such outdated technology... It's more expensive and it's more difficult to build with tubes. They are also less energy efficient.

 

[Vincent Kars]

Just my piece of armchair enginering

I have read that some people have successfully paired the HiFiMan HE-500 (38 ohms) with the La Figaro 339.

Might be a matter of taste. If you like a bloated bass, insufficient damping will sounds good.
If we (here comes the armchair) that a planar has a lower mass than a moving coil, insufficient damping might be less harmful simply because the mass is lower hence the bass suffers less.

23 to 43 ohms depending on the tubes used

40*8=320, get headphones with a impedance at 1000 Ohm or buy a an amp without this high impedance.
Unless you love distortion, don't buy a tubed amp: https://www.audiosciencereview.com/...-wa7-wa7tp-dac-and-headphone-amp-review.7028/

 

[linx]

Can you find the specs on the La Figaro? If it's rated to drive 32-Ohm headphones it should be OK. If you can't find the specs, I wouldn't take a chance.

The specs say 32-600Ω

Personally, I avoid such outdated technology... It's more expensive and it's more difficult to build with tubes. They are also less energy efficient.

I see you have some valid points there

 

[linx]

Might be a matter of taste. If you like a bloated bass, insufficient damping will sounds good.
If we (here comes the armchair) that a planar has a lower mass than a moving coil, insufficient damping might be less harmful simply because the mass is lower hence the bass suffers less.

Honestly, after using the bass deficient he400se for a while, I think I really dislike bloated bass.
I have recently repaired the sound system in my car and had to instantly turn off all bass equalization because I sounded so bad to me.

Unless you love distortion, don't buy a tubed amp: https://www.audiosciencereview.com/...-wa7-wa7tp-dac-and-headphone-amp-review.7028/

Well, I have no idea if the tube induced distortions will sound good to me, I think my best option is to ask the seller for a test listening.

 

[IdleTalk]

The HE400SE's bass won't bloat due to the higher output impedance of amps, because planar magnetic headphones have a flat impedance curve.
However, they are more likely to suffer from an elevated noise floor due to mains hum or insufficient maximum SPL, depending on the dB/V sensitivity of the paired headphones.
I recommend getting a decent solid-state amp with high SINAD as a reference point before beginning your journey with tubes. That way, you can safely enjoy the "flavors" that tubes may offer.