Completely new to Headphone Amps - Guidance Please

Take a look at the Learning center at the headphone.com site. Very useful. 

Or just randomly clicking on threads that involve your headphone choices... Who knows?  Might dig up a gem, otherwise use the search function. 

Well the ATH AD2000 are 60Ohm and the T1 are 600Ohm... I would suggest an OTL tube amp for 600Ohm phones like a Woo Audio 2 or Darkvoice 336/337. For the AD2000s you ideally want solid state, if you don't already own a good DAC I would be inclined to suggest something like a Grace m902/3. Using the Grace with the OTL amp for the T1 would also be a very nice setup but then you're looking at $2000+ ~ what is your budget btw?

I think the AD2k is an excellent choice for getting started; it's neutral and easy to power, so you have a good colorless response and don't need to splash out on amping. I would buy the AD2k and see how it sounds plugged directly into your m-audio firewire 410, I haven't heard it so I can't comment but chances are it will power a 60Ohm phone. The benefit of a dedicated DAC or something like the Grace m902/3 is the sound quality, in a lot of cheaper solutions, soundcards and receivers the DAC is rarely anything special. If your 410 can't power your headphone the tell-tale signs will be distortion on raising the volume, then you can decide if you want to build something around the AD2k or go with a different phone.

With a budget of $400-$600, don't buy a tube amp. To channel the advice of Uncle Erik for a moment, tube amps don't really come into their own below the $1k mark, largely due to using inferior power supplies in order to cut costs. Solid state can be done well at a cheaper entry point than tubes can.

 

In terms of the features you should be looking for... first and foremost, make sure they match the headphones you're looking to pair with them, in this case the AD2K. Generally speaking, low-impedance headphones (100 Ohms and under) require more current than voltage from an amplifier, while high-impedance headphones (100-600 Ohms) require more voltage swing than current. The AD2K is a 40-ohm headphone, so you want a solid state amplifier that can provide plenty of current first and foremost.

 

Next, I'd be researching subjective amplifier synergy with your particular headphone. For instance, it seems common consensus that the Burson amplifiers don't sound very good with the Beyer T1, while sounding excellent with Sennheisers and the LCD2. Why? I couldn't tell you. Perhaps the Burson is just voiced wrong for the T1's. But that's something that a spec sheet won't necessarily tell you, but subjective posts on head-fi will. Of course, take all subjective oppinions with a grain of salt. After all, what sounds good to me, might not to you. But that at least gives you a place to start.

 

Then, should you feel inclined, you can start researching amplifier technology in detail. Opamps Vs all-discrete designs, tubes Vs solid state, passive ground Vs active, balanced Vs single ended, etc etc. It's a quagmire of information that's best tackled slowly, with liberal "reality checks" from your own ears. To quote someone's signature around here (whose name eludes me); "If it measures good and sounds bad, it is bad. If it sounds good and measures bad, you've measured the wrong thing".
 

You might consider the Schiit amps since they are in your budget range and some are tube based. Since you are in the "middle of the Pacific" I don't know how hard it would be for you to get your hands on one. I don't necessarily agree you can't buy a good tube amp for <1k but what do I know.  Short answer: get a Lyr and tube roll until you like the way it all sounds.

$400-$600 will only get you an OTL tube amp* that won't work well with 60 Ohm headphones. The trick is that you need an output impedance lower than the headphone impedance for a good damping factor (worth looking up) for good control over the headphones. OTLs typically have a high output impedance - I've seen them as high as 150 Ohms, which is totally unsuitable. The only commercial OTL is the Zana Deux that is capable of low impedance output. That's because of its 6C33C tubes. If you want low output impedance with tubes, you need output transformers. Those really increase the price. And as was mentioned, cheap tube amps cut a lot of corners. Those can include "mystery meat" power transformers of dubious origin. They often have cheap filtering schemes that let AC ripple into the signal. The power supply isn't anywhere as sexy as tube rolling, but putting pricey NOS tubes in them cannot clean AC leaked in.

Solid state doesn't have output impedance problems - it is almost always low impedance. There are lots of good ones out there. Also, solid state is cheaper since you can get away with inexpensive low power transformers. It's the high power transformers where you have to be careful. One design I like is the M^3; you could commission one on your budget. I have one and it is a fine amp.

* The exception is the new Bottlehead Smack. $500 and it has output transformers. But you have to build it. Still, Bottlehead makes excellent products, the kit will have all the parts, they have excellent manuals, a forum where you can get help, and the DIY Forum here will help you. It's a good deal.

With that said, are Schiit or Little Dot amps bad? They certainly get tossed around a lot here, especially Schiit. Is it a but FOTM thing, or an exception to your rule?

I'm not crazy about the Little Dot power supplies or PCB construction.

Though I'd consider a Schiit solid state amp. I'm not sure about their hybrid. I'm funny about tubes. Either you go all-out for a properly built point-to-point entirely tubed amp or you buy a quality class A solid state amp. (Yes, solid state can sound great.)

I will admit that I might be off the mark here and some hybrids might be good. My hangup is that most hybrids are on PCBs, which I don't like for tubes. Tubes run hot and shouldn't be on something that can scorch and lift traces. They should be on ceramic or Teflon sockets connected with wires that can be replaced. My other hangup is that some hybrids run tubes at the same voltage as the chips, like 12-16V, when the tube is designed to run at over 200V. Those sometimes just have the tubes there to add a little tube flavor and claim that it has tubes. I think tubes should be run as designed, not as decoration.

Of course, I could be wrong. If someone disagrees, please post and explain.

My position is that you either use tubes and really do them right or go solid state and really do it right. The difference is that it costs a lot less to really do solid state right. The difference is that it's a lot cheaper to get a great solid state amp. If you want a budget amp, then do solid state well. You'll get much better sound than a compromised tube amp. Hybrids might be an exception, but I need to learn more to be confident about that.

Personally I've found high impedance cans to benefit from cheap OTL amps as opposed to cheap solid-states. Similarly I'll recommend solid-states over tube for low impedance. I don't buy into a lot of the hype surrounding amps; match tube-for-tube and they'll sound the same, likewise match opamp-for-opamp and you've got the same sound. Tubes and opamps are the sound and in so many cases you have a $500 amp built around a $10 op-amp, reviews comment on how good one amp is compared to another but all they're doing is comparing these $10 replaceable chips.

 

This general statement that 'solid state can be done well at a cheaper entry point than tubes' is too general, I would consider that incorrect when it comes to higher impedance cans.

I disagree about the tube-for-tube parity between amps. The same tube will sound different for a few reasons. One, each amp has a different bias voltage for the tube. Change that and you change the linearity - you can find graphs of this in the datasheet of any tube. Two, the circuit it runs in changes the sound. Run it as an OTL and it will sound different from running it with an output transformer. Three, the power supply is critical. Whether the rectification is diodes or tubes makes a difference. Cheap amps let some AC ripple directly into the signal path. Measurable and audible. Fixable, but you need good filtering and chokes that add to cost. Whether the filaments are run on AC or DC matters, too. Running AC can introduce noise into the signal if the amp isn't built well. DC costs more money. Lots of other stuff, too.

The circuit, power supply and build quality all play significant roles. You're better of with inexpensive repro tubes in a good amp than fine NOS tubes in a bad one. AC ripple will be amplified exquisitely by the rarest of rare Western Electric tubes.