Using a speaker amplifier to drive Headphones

[karlsushi]

I have Audeze LCD2s and although I love my Feliks Elise headamp that I use to power them, I can't help thinking they need a bit more oomph. Planars are, as I understand it, very grateful of large amounts of power/current.

I potentially have a Pass Labs Aleph 3 surplus to requirements (once back from repair) which is too good an amp to just move on, so I have been wondering about using that as a slightly audacious way of driving the LCD2s.

I have read the odd report of people using full-sized speaker amps on planar headphones (even with power ratings of 100W+) and wondered if anyone had any views on how ridiculous an idea this might be (subject to the obvious investment in the correct cables to link speaker outputs to xlr headphone inputs).

I would probably use a stepped attenuator for volume control, but not sure if ensuring the appropriate volume control would be part of the considerations here.

The Pass puts out 30W into 8 Ohms, so presumably a lot less into the 72 Ohm load of the LCD2s, so not quite as crazy as it might first appear bearing in mind the power of some headphone amps. Or is it?

 

[Lawrence001]

If that's a class A amp I'd probably avoid using it for headphones just due to the heat, but I'd also consider stability into high impedance loads (although low is probably more risky). There are impedance transformer boxes available with headphone jack out but these will reduce efficiency further.

I ran my HE6 directly from a 1000wpc ice Power amp so in theory it's not ridiculous.

 

[karlsushi]

If that's a class A amp

yes, it's a single-ended pure Class A design

 

[griffo104]

That's way overkill for an LCD2. They aren't that difficult a load, most of the people I have read about doing this are driving Abyss 1266 or Hifiman Susvara which are very silly planars that are very difficult to drive, much more so than the LCD2.

The problem with OTL and planars is more down to impedance matching than power,

If you want a serious headphone amplifier then look at the SPL Phonitor series, that would have more than enough power for the LCD2.

I'm using the headphone amp on my RME and it drives the M1570 planars with some ease.

 

[Lawrence001]

This is true, not many valve OTL amps will drive a pair of low impedance planars (I have one that works but it kicks out 1 watt which is rare).

A pass amp is definitely overkill price wise, it's been optimised for speakers so you're paying a high price and asking it to do something it wasn't designed for.

The THX AAA amps are good for planars and don't cost a bomb, Monoprice and SMSL make them IIRC.

 

[karlsushi]

I hear what you're saying, but as I mentioned, the amp is surplus to requirements, so it's (kind of) not costing me anything to try out (just some cables). I guess I thought it was worth a try just for the outlay of the cables, but want to be sure I'm not going to damage anything.

Sounds like you're saying there's nothing 'technically' wrong with the idea!?

Of course I suppose by trading in the Aleph 3 plus the Elise, I could probably get a pretty decent headamp, but I'm lazy and find it much easier to buy stuff than sell it!

 

[Hornucopia]

I've used an amp this way for years, running Wharfedale Isodynamics and am now putting Ether 2s through one (Peachtree iDecco) the same way, via a simple junction box with a couple of resistors (thanks Ali)
The first set-up I just split a headphone extension lead and put phono plugs on, using just one 'earth'/negative lead

 

[griffo104]

The professionals view of doing it.

Pass Labs do get a fleeting mention

 

[JamieMcC]

Fwiw if you didn't want to diy some cables to try Hifiman make a adapter box for exactly that purpose for use with their planar headphones with a XLR socket.

I know several LCD2 owners who say the Bottled Sex 2W single ended triode is superb with them. I have the amp but have not heard the LCD2 on it.

I've used the Pass ACA 6w speaker amp in the past to drive the HE6 and it worked superbly well. Pass Amps often get good feed back from those who run harder to drive headphones.

 

[Headcoat]

@karlsushi Out of interest how do the LCD2's sound with the Elise?

Reading reviews of the LCD2's they sound right up my street, and I have the Feliks Elise too.

Personally I've had no problem running lower impedance headphones (Nighthawks and Meze 99 Classics) from the Elise. To my ears the impedance 'mismatch' seems to have no audible impact. There's certainly enough power.

 

[karlsushi]

Out of interest how do the LCD2's sound with the Elise?

At the time I was researching a headphone amp, I had a couple of requirements that led me to it, beyond simply sound quality. Firstly, I was rigidly determined to get an amp with valves and secondly, I needed something with pre-outs so it could double-up as a preamp. I did a few demos (including notably an LTA MicroZotl MZ2 and a World Audio Designs HD3S - the latter of which was a much better amp in my view - didn't get on with the LTA at all, contrary to the consensus out there on these). But I came back to the Elise.

It does a great job of driving the LCD2s (the LTA really didn't!!) and really I shouldn't be considering anything else, but my circumstances have changed a bit as I no longer need the pre-out function.

Also, having discovered you can get that same valvey smoothness I was craving from decent Class A, I am wondering about something solid state, but with a bit more beef given everything I read about planars. It's really only when I crank it up very loud that I start to notice things losing grip (slightly), but at low to moderate levels, it does a fabulous job and is probably all the headamp I ought to need (but we all know how this hobby goes!).

The only warning about the LCD2s with the Elise is that both are pretty warm-sounding, so it may just be too much of a good thing for some people. Personally, I love the combination.

If you were a bit closer I'd happily drop them round, but if you're ever driving past the East Midlands give me a PM.

 

[Headcoat]

At the time I was researching a headphone amp, I had a couple of requirements that led me to it, beyond simply sound quality. Firstly, I was rigidly determined to get an amp with valves and secondly, I needed something with pre-outs so it could double-up as a preamp. I did a few demos (including notably an LTA MicroZotl MZ2 and a World Audio Designs HD3S - the latter of which was a much better amp in my view - didn't get on with the LTA at all, contrary to the consensus out there on these). But I came back to the Elise.

It does a great job of driving the LCD2s (the LTA really didn't!!) and really I shouldn't be considering anything else, but my circumstances have changed a bit as I no longer need the pre-out function.

Also, having discovered you can get that same valvey smoothness I was craving from decent Class A, I am wondering about something solid state, but with a bit more beef given everything I read about planars. It's really only when I crank it up very loud that I start to notice things losing grip (slightly), but at low to moderate levels, it does a fabulous job and is probably all the headamp I ought to need (but we all know how this hobby goes!).

The only warning about the LCD2s with the Elise is that both are pretty warm-sounding, so it may just be too much of a good thing for some people. Personally, I love the combination.

If you were a bit closer I'd happily drop them round, but if you're ever driving past the East Midlands give me a PM.

That's very kind of you, the LCD2's would be a way in the future consideration; money is tight for the foreseeable after a bit of a spending spree.

I've actually bought a Schiit Aegir to use as a power amp with the Feliks Elise.

Re. class A headphone amps, I have an Arcam rHead that I need to get around listing in the classifieds. Almost mint, I mainly used it for work (now retired) and bought an Echo and then an Elise for music headphone duties. Might be of interest to you?

 

[karlsushi]

Might be of interest to you?

Hmm. Not sure. Feels like a step backwards from the Elise, albeit Class A SS. I'm probably looking for something higher up the ladder and with a bit more power, but thanks for the offer.

 

[Headcoat]

Hmm. Not sure. Feels like a step backwards from the Elise, albeit Class A SS. I'm probably looking for something higher up the ladder and with a bit more power, but thanks for the offer.

Fair does. Yes, it is a step down, mentioned as it is Class A without considering that point.

 

[Speedy]

I remember this was (and is) pretty popular to do with the Hifiman HE6 and nowadays the Susvara as well. At a meet once I saw someone had brought a setup like that and they attached a step by step list of precautions for people to prevent damage to the headphones. Besides the speaker amp imparting its tonal and technical characted to an LCD2 (much like any headphone amp would) I'm not sure if there would really be anyn benefit to the extra power - LDC2s are really efficient whereas those hifimans that people usually use with speaker amps are notoriously inefficient. I believe the HE6 was around 80db/mw which is in speaker territory!