[nxmehta]

I'm brand new to using headphone amps and DACs.  One of the main reasons I'm looking into this now is that I want to get some nice monitors for my PC, and almost all of them lack a headphone out.  So I figured it's time to get a real headphone amp that can double as a switch.
 
My budget is $250, and my source is a laptop.  I listen with Sennheiser IE8 IEMs and Denon AHD2000's.  I may get a pair of Sennheiser HD 650's soon which I've heard really benefit from an amp.
 
Here's what I'm looking for in a heaphone amp + DAC:
 
1. USB input (analog and other digital inputs are a plus but not required).
2. Headphone jack output (1/8" would be the most convenient)
3. Speaker output- I don't know if I should be looking for a line out or a pre amp out.  This output will be going to active monitors like the Audioengine A5's.  What's the difference here?
4. The ability to isolate either the headphones or speakers- e.g. when I plug in the headphones I want the speakers to turn off.
5. The ability to control volume for both the speakers and headphones through software (Windows or Linux).  I've heard that a lot of these headphone amp + DAC USB combos *require* you to change volume via knobs.  For some reason they don't support changing volume in software even though they are using USB?
 
I've been searching around, and I'm finding it difficult to get information about #5... for example, it doesn't look like the NuForce udac-2 fits the bill, even though it's highly recommended around here?
 
Any help would be really appreciated for someone who's looking to take the headphone amp jump but doesn't know which way to go yet

 

[alistaire]

Unless you're looking for something portable, I really wouldn't combine amp and DAC, particularly in your case. The best setup for you (from what I gather) would be a USB DAC with a switch (either two separate analog outs, or a separate switch, or you can just swap cables) to switch between headphones and speakers, and a separate headphone amp. Using a headphone amp for speakers is pointless (not enough power), but the DAC would help. Plus, you've got powered speakers, so amping the signal wouldn't help much, anyway. So:
 
1. Pretty widespread.
2. Universal, either 1/8 in, 1/4 in, or balanced (XLR). 1/4 to 1/8 adapters are easy, if you need one.
3. You just need a clean analog signal for your speakers, so look for a decent DAC which you can use with both.
4. Just a matter of switching. There's different ways of doing it, but they'll all do the trick.
5. Won't work, sorry. A digital signal has no amplitude (volume), so changing the volume on your computer won't change the digital signal it outputs, no matter how you do it. All amps (or preamps, for speakers) have volume controls. If you use your computer's analog out directly to an amp, it will work, but the sound won't be as good as if you used a better DAC, plus your computer volume probably won't cover the full range, depending on what your amp's volume is set at. It'd just be like two volume controls on top of each other. Sorry, you're stuck with knobs. The good news is that unless you've got a ridiculously long cable, you'll never be that far from the knob when you need it.
 
So, some places to look:
Portable amp/DAC combos: sometimes cheaper, you only need one, sometimes with passthrough so you can only use the DAC part with your speakers. Check out HeadAmp (Pico family), iBasso (D10, others), and RSA.
DACs: The Nuforce uDAC (both 1 and 2) are good, and well priced. DIY options are cheap, if you can solder. Otherwise, they can get expensive fast.
Amps: Little Dot or Schiit, maybe. Combined with a DAC, a decent amp will probably put you over $250, though, as will a lot of things here. Used helps; check out the FS forum. If you need to buy in pieces, buy the amp first, then the DAC. (Bad DAC to good DAC makes a big difference, but a DAC is useless without an amp.)
 
Most of all, read the reviews here.
 
Welcome to Head-Fi, and sorry about your wallet.

 

[ThePhoenix924S]

While I totally agree that using separate devices is better in the long run, I would recommend the Audinst HUD-mx1, which is a DAC with a built in amplifier.  It is $180, and while it is USB only, it DOES have RCA outs for use with speakers or a stand-alone amplifier.  It also has both a 6.3mm (what the HD650 uses) and a 3.5mm headphone jack.  I'm using one right now with my own HD650s and think it is an extremely useful device.  And since it's under-budget, that will put you ahead in saving up for a dedicated amp later on.
 
Edit: Oh, it also supports the alteration of volume from the PC, so you don't HAVE to use the volume knob (though I don't see why you wouldn't want to, much more accurate than changing the PC's sound output and as it is something you can physically change quickly, much more useful in my opinion.  All to your own however.)

 

[Satellite_6]

I love my EF2A + RCA 5654 tubes with the HD 650s. It has RCA inputs + the USB DAC. I don't know how it compares to anything else though, just throwin' it out there. 
 
About number 5, I'm confused, can't you just change the volume in the program you are using or windows? 

 

[alistaire]

Quote:

About number 5, I'm confused, can't you just change the volume in the program you are using or windows? 

With most DACs, changing the volume on a computer won't affect the signal, because it's digital (so it has no amplitude to change). It's possible to also incorporate a separate signal in the USB signal to indicate amp output volume, but that means the amp has to have access to that data, which is a lot of work unless it's combined in the same box (an amp-DAC like Phoenix mentioned above), so most makers just give you knobs. They are more precise, if not always as convenient.
 
@nxmehta: You may have trouble finding one amp that will optimize all your headphones. From what I've read here, IEMs like portables, Denons like solid-states, and the Senns like tubes. The Schiit Asgard might be a decent compromise, but read around first.