[JovialThug]

I keep an eye on this site whenever I'm in need of a new piece of audio gear (as you already know there is plenty of great info!), but this time I just don't quite have my head around portable DAC/amp combos. My current setup is the O2+ODAC with a pair of Beyerdynamic DT990s; I love this setup, but I don't have a fixed place my computer these days and I need the flexibility of being able to drag my DAC/amp around the house with my laptop. Therefore I've been looking at portable options. An obvious pick was the JDS Labs C5D, but I don't need a device with a battery (as it will always be connected to my computer). Size isn't an issue. I haven't set a firm budget, but ~USD300 would be a rough estimate.
 
In summary; is there a combo of DAC/amp that is USB powered that is comparable to the O2+ODAC? As I reference let's say they will be driving the Beyerdynamic DT770 250 ohm (I don't have these, but I'm keen to get closed headphone that is similar to the DT990s; keen for suggestions of headphones too!), thanks for any help :]

 

[cel4145]

This is an interesting question. A lot of the portable ones do have batteries, and then you need one that can power 250 ohm headphones. The Geek Out 1000 is one you might consider: http://www.amazon.com/Geek-Out-1000-Headphone-Amplifier/dp/B00JD0CV3M

 

[kramer5150]

Isn't the choke point on these kinds of circuits the USB power itself?.  Theres only so much you can do with 5V peak available.  Splitting it into +/- AC, and factoring in circuit efficiency losses leaves little headroom for V-RMS swings needed with high impedance loads.  If you are a quiet volume listener that might change things a little.

 

[JovialThug]

Thanks for the answers, that info gives me a good place to start. An alternative question; if I were to use the Geek Out 1000, what impedance headphones would I realistically be able to use? One review I've looked at said it paired up well with the HD700, so at least 150 Ohm? As you can tell I am not very savvy with the science of audio equipment, otherwise I could probably derive this answer myself! I mainly listen to punchy electronic music (which I listen to fairly loud), but also a lot of ambient stuff.
 
EDIT; potentially the Geek Out 450 could be a good compromise? The 1000 would be great, but the way my country's (New Zealand) import tax works is that parcels + shipping generally have to be under NZD400; the 1000 is getting dangerously close to this and I would end up paying more in tax.
 
I might have been a bit eager trying to power 250 ohm headphones off USB power. I'm in a bit of chicken/egg situation; I need to find a pair of nice closed headphones (but I don't know what I could realistically power off USB) and I need a DAC/amp to power them (but I don't know how much power I'll need from the amp) :S. I'm currently using the ATX-M50x connected to my laptop, and they honestly don't sound that bad, but I am missing that oomph in the bass (I know these HPs are known for their bass, but my DT990s with the O2+ODAC sound much bigger to me). This track, for example, sounds enormous with my proper setup, but underwhelming with my laptop setup: https://www.youtube.com/watch?v=0VDTHlANJC0

 

[cel4145]

I have no direct experience with the Geek Out products, so I can't help you with those questions. Best thing is to see if there is an impressions thread on Head-Fi for them and see what headphones people are powering with them.

 

[cuiter23]

The GeekOut is probably the best portable USB AMP/DAC combo out there. The resolution and power it provides (especially the 1W GO) is insane for such a small unit. 

 

[JovialThug]

Thanks for the further replies. It really does seem that the Geek Out line are winners! I am now looking at the 80 ohm version of the DT770s and I'm leaning towards the cheaper GO450. Enough people out there are driving thier DT770-80s with their iPods/laptops so I figure the GO450 would be a good match. Providing I lock this combo in I'll report back with the results!

 

[kramer5150]

Any reason you're not considering the 32 ohm model?  That would be an easier load for these kinds of amp circuits.  They are primarily current output devices, and are (theoretically) more voltage-swing limited.

 

[JovialThug]

The 80 ohm version, from what Ive read, has more bass emphasis.