[hojomojo96]

Okay, so I've been doing a lot of research, and the world of vacuum tubes has me utterly confused. There is, for example, the Aune T1, the Maverick Tubemagic D1 and A1, and god knows what else in this price range. Tubes in the DAC, in a preamp, or a "true" headphone tube amp. Basically, what should I be looking for in the price range? Is it too much to expect to find something using the tubes in both the DAC and amp, not just one or the other? I would like some amount of upgradeability, for the future. For the record, my source is going FLAC files from foobar out of a computer motherboard, or an old Creative Sound Blaster Audigy 2 sound card I have lying around (speaking of which, any opinions on which of those I should go with?), and my headphones will be Mad Dogs. I tend to like a darker sound with large soundstage. This will be my first foray into tubes
Thanks!
 
EDIT: Oh, also, can someone clarify what the purpose of a preamp is exactly? I'm not exactly clear on why it would produce "better" sound quality than an amp alone.

 

[p a t r i c k]

   
EDIT: Oh, also, can someone clarify what the purpose of a preamp is exactly? I'm not exactly clear on why it would produce "better" sound quality than an amp alone.

 
The classic audio amplifier design has two circuits. The first circuit includes the gain control and indeed that circuit exists primarily so that gain is adjustable. The gain is adjustable by the user using a knob called "volume". The second circuit actually amplifies the signal in the first circuit to a much greater degree, such that it is powerful enough to drive some speakers.
 
Sometimes the amplifier is split in two. It will have two boxes each with a separate power supply. When the amplifier is like this the part with the first circuit is called a "Pre Amplifier" and the part with the second circuit is called a "Power Amplifier".
 
Often headphone amplifiers are in fact just the first circuit of the classic amplifier design because the output of the first circuit is powerful enough to drive headphones. So sometimes headphone amplifiers can be used as pre amplifiers.
 
I'm afraid I cannot help with the other question regarding valve ("tube" in US) amplifiers as I am someone who prefer solid state designs.

 

[tomb]

I think the title of "pre-amplifier" has a very specific meaning in stereo equipment.  It is intended to "collect" all of the various sources that might be connected into a system and provide the primary signal amplification.  That means that it has switching to handle multiple source inputs and that it outputs to a standard that can be used to feed a power amplifier.
 
In real practice, a pre-amplifier provides voltage signal amplification, only - with little to no current amplification (sometimes called buffering).  That usually means that a good pre-amplifier has very good S/N specs.  It is not intended to power a load of any substance, however.
 
In common stereo systems, the headphone out is usually provided in the pre-amplifier section.  This was typical because many headphones were often regarded as very high-impedance loads with little to no current draw (>600 ohm or crystal sets?).  This changed through the years as dynamic headphones became popular with much lower impedances.  Headphone out connections were often provided with their own separate amplifier circuits, or in the case of many receivers (a pre-amp and amp combined), perhaps a cheap resistor off of the power amplifier output.
 
There are many flavors of pre-amplifiers - some with headphone out capability, some not.  It's really up to the user to determine whether a particular pre-amplifier is really an equivalent of a dedicated headphone amplifier.
 
As to your specific questions, I think orthos (Fostex TR-50rp's) are a poor choice to connect to a pre-amplifier.  Most orthos require lots of current - even a power amp, period.  That's not the specialty of typical pre-amplifiers.
 
About DACs - you will find with a few exceptions that most "tube" DACs are simply DACs with a tube-flavored amplifier circuit applied to the output after the primary DAC circuit.  Most, if not all tubes (and I am a tube proponent) are simply not able to provide the super-low-noise, current-to-voltage conversion that most quality DACs need.  Tubes were primarily designed to amplify voltage and use very high voltages to attain reasonable S/N ratios.  Conversely, DACs output miniscule voltages and currents.  You really need some transformers in the circuit to apply tubes directly to a DAC and both introduce significantly more noise to the miniscule DAC signal.
 
For the same reasons as above, you won't see many tubes applied to a phono pre-amplifier, either.

 
This will probably cause a flame war, but yes - a dedicated DAC of some sort will probably give you better sound than your motherboard's output or a Creative Labs SoundBlaster.