elnero wrote quite a good summary which I think is very helpful:
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| Originally Posted by elnero /img/forum/go_quote.gif Welcome to Head-Fi, sorry about your wallet. 
I'm not sure how much of an understanding you have so I'll try to go right to the beginning in a simplistic form. mp3's, m4a's, etc. are digital files, they require that the digital signal be converted to analog via a DAC (Digital to Analog Converter) and then that signal is amplified for output to headphones or speakers. Many digital audio players do not allow you to bypass their internal circuitry at all, some like the iPod's have a line out that bypass the internal amplifier allowing you to amplify the signal via a separate amplifier. A very few other's have a digital output that will bypass the internal DAC allowing them to be used with a separate DAC. So the online store you contacted is right, the signal coming from the line out of an iPod/iPhone is analog so a DAC is useless. What people are doing when they're using the line out of an iPod is bypassing the iPod's rather cheap/weak/noisy internal headphone amplifier with one of better quality that is quieter and better able to drive the headphones they use. Using a portable amp on the go is a bit of a trade-off, it becomes a matter of personal preference by the user whether the increase in sound quality is worth the extra bulk. This also goes for ripping to a lossless codec for portable use, lossless takes up a lot more storage space and battery life will be decreased and it's debatable how much of an increase in sound quality one would hear via a portable player. IMO, if portability with the least amount of bulk and the most selection of music is important then I'd suggest ripping to a decent quality lossy codec and not worrying about an amp for portable use. For myself I use a portable DAC/Amp via my computer both at home and work. The Pico's DAC is very high quality and has been compared favorably with much more expensive DAC's. Many of these portable DAC/Amp solutions are made so that the amplifier alone can be used via a line out like that of an iPod's but can also be used with a computer as a DAC/Amp via a USB input on the DAC/Amp. This allows for some very high quality listening via the computer. Of course the quality is going to rely on the quality of the DAC/Amp itself so some will be of minimal benefit while others will have a bigger effect. It's important to note that not all portable DAC/Amps offer the same features. The bulk of the recent ones can be used as an amp only or as a DAC/Amp with a computer via a USB input as noted above. A few others though offer coaxial and/or optical inputs allowing the user more options to hook the DAC up to things like CD players or DVD players that have these types of outputs. The trade-off here becomes bulk, additional input/output options means larger size to accommodate them. It's also important to note that a portable amp is also a bit of a trade-off, generally a good quality home amplifier will do a better job with harder to drive headphones. So really there is no right or wrong decisions, it comes down to when, where and how you plan to listen, what are your priorities what are your preferences. For myself I don't tend to listen a whole lot on the go, when I do decently ripped lossy files via an iPod is good by me. I tend to listen quite a bit at work and though I don't get to listen much at home I do prefer those sessions to be high quality. I'm also on a somewhat tight budget so being able to transport that system to and from work is a huge bonus. That's why I went with the Pico DAC/Amp, high quality DAC and portable amp in a tiny box that's easy to cart back and forth. |
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