How does an amp make a pair of headphones sound better?
Mar 18, 2011 at 12:52 AM Thread Starter Post #1 of 10


New Head-Fier
Mar 5, 2011
Just wondering about this. I recently bought a pair of Senn HD555's, and I'm just plugging them straight into my laptop's audio port, no amp. I've heard that you don't really need an amp for these cans, but I was just curious if I should get one/which one/how would it make them sound better. If that made sense..
Mar 18, 2011 at 1:30 AM Post #2 of 10
By itself, an amp will make the HD 555 sound better by sending a more powerful signal to the phones.  However, it can also magnify whatever sounds bad in the chain.  So, if your laptop has a poor quality sound card - like most laptops, and if you are listening to poorly recorded or low bit-rate mp3s, then the bad sound card or the low quality music will have its bad quality amplified.  This is why people here on head-fi start tail-chasing - new headphones leads to new amp which leads to new dac (in place of sound card) etc.  Every time one piece in the chain gets better, the weaknesses of the other pieces are apparent.
I use an HD 595 at work which has the same drvier as the HD 555. I have tried it straight out of my laptop, with a Lisa III and with a Matrix M-Stage.  Both amps make a difference.  I generally like the M-Stage better because it delivers more power but both amps make a difference.
So what is the difference?  With an amp the sound is fuller.  There is more space between instruments.  The base is more pronounced.  There is more detail in the music.  Think about what it does to make your music louder.  People turn up the volume to put more power behind hte music and hear it more fully.  The more powerful the amp, the more it puts support behind the sound and gives you the fuller sound of high volume but without the volume turned up so high.
I think the HD 595, and by extrapolation the HD 555, does decently without an amp.  An inexpensive portable amp will do little more than add volume and a volume switch.  I think they do pretty well with the M-Stage - which is around $250. 
Mar 18, 2011 at 2:28 AM Post #3 of 10
All of the stuff I listen to is FLAC or better, so I know it's not that. My main concern is price, as I bought the HD555's because they were relatively cheap (got them for $85) and I wasn't looking to spend more than that on an amp. (Unless I absolutely have to..)
Any smaller amps out there that do the same/similar thing? Such as ones that run through the computer's USB port?
I probably sound like a noob.. because I am haha. Bear with me.
Mar 19, 2011 at 8:24 PM Post #5 of 10
I'm not sure about the 555s as I've never heard them but in my experience amps can make or break some phones.  Some amps can make phones you like phones you love.  Sometimes no amp will make you like a particular set of phones, in which case the amping isn't the problem, the cans are.
Mar 19, 2011 at 9:08 PM Post #6 of 10
Unlike some people (perhaps most) around here, I don't think an amp is necessarily positive. I only have an E9, however I find it hard to believe any amp can have zero losses. Let's take a look at the signal paths with and without an amp:
a) dac->line out->cable->amp line in->amp->jack;
b) dac->jack.
Seems to me that, if the source headphone output is good enough, it will sound better than a signal that has to cross an extra two connectors, a cable and two PCB segments.
My experience seems to confirm this. Audio straight from the source headphone output is more detailed and with better treble and bass extension. However, it often lacks the dynamic range and speed the amp can muster. This alone can make it a more engaging listen.
I cannot talk about the 555s, but the 595s gain a bit of dynamics when amped, but definitely not enough to warrant buying an amp for them.
Depending on the quality of your laptop's DAC, you might be better off getting an external DAC+amp like the E7.
Mar 19, 2011 at 10:56 PM Post #7 of 10
I don't have much experience with amps myself, but from the 2 amps I've listened to, the benefit from amps isn't as much as people make it out to be a lot of the time. I have not heard the hd555 with an amp before, but I will give you an example from something I have heard. A pair of ~$100 m50s are noticeably better when paired with a ~$130 fiio e9. The sound is much fuller, etc... For the sound quality difference I got from amping, I would probably pay an extra $20 for the m50 as a headphone. The difference is nowhere near as significant as if you had just bought an unamped headphone for 230.
If you're looking to squeeze the most out of your hd555's then you should by all means do this, but even for a cheap desktop amp like the e9, you'll likely even be better off just buying another pair of headphones with that money. Portable amps tend to give you even less of a difference.
Considering how you said "unless I absolutely have to..." I'm getting the feeling you're looking for a sort of bang for the buck kind of scenario. I think in your case, you will probably be disappointed by the sound quality increase from an amp.
Mar 20, 2011 at 1:37 AM Post #8 of 10
Amps are all about control, not necessarily volume.

Keep in mind that headphone drivers are a kind of motor. The amp has to move a voicecoil and a cone back and forth.

The better the amp, the more control you have. A poor amp might let the cone continue back a bit longer than it should before stopping the cone and moving it in the other direction. This can sound sloppy and poor.

A good amp puts a firm hand on the driver, starting and stopping it with authority.
Mar 20, 2011 at 6:18 PM Post #9 of 10

Any smaller amps out there that do the same/similar thing? Such as ones that run through the computer's USB port?  

There are plenty of choices like that for you out there.  However, if it is using a USB port then in is a  DAC or AMP/DAC not an amp.  Though with those HPs, using a laptop and  FLAC you may want to think about DACs too.
Mar 20, 2011 at 6:24 PM Post #10 of 10
Actually, your HPs are low impedance with good sensitivity so depending on what you listen to and how loud you probably don't NEED amping - so this really opens you up to a lot of portable AMP/DACs out there.  My Fiio e7 runs out of power sometimes with my hd650's but this should not happen with the 555s.  (note that I have never even listened to HD555s before so I can't recommend anything)

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