Does absence of an amp and/or dac really bottleneck the HD 598?

No, it won't make a huge difference unless you're getting noise or not enough volume. You'll get less distortion, but there's no telling how audible that will be, and it probably won't be worth $100.

 

If you do upgrade, avoid the uDAC and make sure what you get has low output impedance. That's most important for the HD598.

As a 598 owner of about two months, I'm not sold on spending a lot to upgrade the source/DAC.  You are correct, it's really an easy headphone to drive (think Total Airhead).  It would be nice if you could audition something else with them just for the reality check.  You are also correct that there are much larger differences between cans than between amp/Dacs for the money.  If you really want to pick nits, fussing with dacs is a good time killer but the rewards are likely to be small.  IMHO.  

I've owned and enjoyed my HD 598s for about a year now, I can tell you straight off that an amp makes a huge difference compared to the line out from a CD player, or the CDPs headphone out. There is a huge increase in clarity and definition, and the bass is toned down a little bit.

 

I can also tell you conclusively that, even though my iPod classic drives it to a high SPL, the sound is definitely lacking energy and definition, so an amp is a huge, huge improvement here.

 

Just food for thought.

Is it worth it? Maybe, what's the quality of your current DAC? Is it just onboard sound? Or an aftermarket sound card? If you have a high end aftermarket sound card, a FiiO E7 might actually lead to a degradation in SQ.

 

Some amps make a difference, some amps don't, some amps are praised for the difference they make in sound but they really don't.

 

SQ-wise DAC upgrades will always be more of an improvement than amps since amps aren't designed to make SQ better as much as they are to make the sound louder.

Look at it this way: your soundcard is a dac and amp.
And, the only reason you should consider upgrading from that is if there is a product that you feel certain gives you higher performance than your soundcard.

I, for one, am not convinced that the slew of $100 dacs and amps out there offer much in the way of improvement over decent onboard sound.
That doesnt mean, however, that a nice stand alone dac and desktop amp wont be a revelation to you.

Remember: it is not about power only. It is also about signal degradation.
Nicer amps allow more of the original signal through.
Edited by TheWuss - 11/13/11 at 9:08am

 

I'd say the differences in opinion come more from cognitive biases than product changes.
 

DACs aren't designed to improve sound quality either. They're designed to reconstruct it without error.

 

DACs have one job, which is to make an analog electrical signal out of a digital signal with minimal noise and distortion. Amps have one job, which is to make that analog signal more or less powerful. Amps are more important overall, actually, because DACs don't interface directly with the headphone. A DAC that does its job well will do its job well in 99% of all cases. An amp that does its job well with one headphone can do poorly with another, depending on that headphone's impedance curve and sensitivity. You can get a good DAC and use it for all headphones. You need to ensure that your amp matches the headphones you're using, because each headphone is different.

 

Headphones have one job too, which is to reproduce that analog signal as sound waves with accuracy. But there's so many variables in a headphone that they are by far the most complex and important factor.

Edited by Head Injury - 11/13/11 at 9:11am

That might be true, thing is a 598 will still sound like a 598 without an amp or a good DAC... the addition of such could/would take it to the next level, some think it's worth the money while others don't.

Gear that's not really designed for headphones (especially "old" gear) often has high output impedance. You may want to try plugging the headphones directly into the motherboard, and if you lose a lot of mid-bass (and like it) you might want an upgrade.

I have the similar HD 558 and am in the same dilemma as well. I'm considering the E7, D-Zero, and E10 right now (mostly for the DAC). From what I read, the improvements will mostly be minor, at least, until you still getting into the "expensive" stuff.

 

On an unrelated note, how do you feel about the M50 to HD598 upgrade? I'm looking to get a pair to complement the Sennheisers so just curious about the SQ difference.

A bunch of people convinced that the differences they hear are the result of the equipment, and not their own subconscious expectations and mood. The mind is incredibly powerful, and no one is immune to it.

 

Some people have more biases at work than others. Some people have biases working in the opposite direction, and they won't hear differences that are real and audible.

Edited by Head Injury - 11/13/11 at 9:33am