Headphone Amp/DAC for around 100$

Always look for the following in a DAC:

Low Total Harmonic Distortion ( THD % ):  You want .005% at worst case and 120dB best case

Wide frequency range ( Hz ):  You want something that goes from at least 20Hz -20kHz and 5Hz - 48kHz is better

High Sample Rate ( kHz ):  You want something that does at least 44.1kHz ( usually 48kHz ) and 192kHz is better

Always look for the following in an Amp:

Low output impedance ( Ohms ):  You want something 5 Ohms or below or match your headphone impedance but not more than 150 Ohms

Wide frequency range ( Hz ):  You want something that goes at least 20Hz - 20kHz with 2Hz to 100kHz preferred

Output power ( Watts ):  You want something that outputs at least 120mW and up to 1W is preferred ( constant voltage source )

Low Total Harmonic Distortion ( THD% ):  You want .005% at worst case and 120dB is best case

Keep in mind your budget is going to limit these specs and a portable amp is not going to always meet or exceed these specs.  I personally use the Bithead which I really like.  It is small, has a decent DAC, and the amp is nice too.  I have had it for years so I know it is built really well.  It runs $149 and is worth every penny.

I think the FiiO E7 is a nice device as well, but some have had failure problems within the first few months of operation.  Both Amp/DAC combos will work fine for you, just go with the one you think has the best reviews and better specs.

Bithead:

http://www.headphone.com/headphone-amps/headroom-total-bithead.php

FiiO E7:

http://www.amazon.com/FiiO-E7-Portable-Headphone-Amplifier/dp/B003E6K1VK

Quote:

Originally Posted by NA Blur 

Always look for the following in a DAC:

 

Low Total Harmonic Distortion ( THD % ):  You want .005% at worst case and 120dB best case

 

Wide frequency range ( Hz ):  You want something that goes from at least 20Hz -20kHz and 5Hz - 48kHz is better

 

High Sample Rate ( kHz ):  You want something that does at least 44.1kHz ( usually 48kHz ) and 192kHz is better

---

Always look for the following in an Amp:

 

Low output impedance ( Ohms ):  You want something 5 Ohms or below or match your headphone impedance but not more than 150 Ohms

 

Wide frequency range ( Hz ):  You want something that goes at least 20Hz - 20kHz with 2Hz to 100kHz preferred

 

Output power ( Watts ):  You want something that outputs at least 120mW and up to 1W is preferred ( constant voltage source )

 

Low Total Harmonic Distortion ( THD% ):  You want .005% at worst case and 120dB is best case

Some of this isn't great information.

0.005% THD is very conservative. You only need less than 0.05%, but the lower the better.

5-48kHz isn't better, because you can't hear that high or that low. What's much more important than frequency range is frequency variation (the +/- number often added at the end of the frequency range). Look for something like +/- 0.2 over 20Hz-20kHz, with 0.1 being better.

192kHz isn't better. 192kHz digital audio actually causes problems. 44.1kHz is just as good, and better in some cases. Most DACs will publish 192kHz if they support it, but you shouldn't use that setting. Chances are the files are in 44.1kHz anyway.

Not more than 150 ohms? I'd say not more than 10 ohms. 150 ohms is enough to color every headphone in production. The rule is you want an output impedance equal to or less than your headphone's impedance divided by 8. You SHOULD look for something with 1-2 ohm output impedance regardless.

Watts isn't always a good way to judge amp power, because it varies greatly with impedance. Voltage is perhaps more important. Use Tyll's data on Inner Fidelity to determine the voltage required to get your headphones to 90dB, then multiply it by 10 to be safe. If the manufacturer only publishes power output in watts, post it here (and the load it was measured with, like 32 ohms or whatever) and I'll help you figure out the voltage.

U should consider the fiio e10 too.