[cactus_farmer]

Not being an electrical engineer I don't know about voltages and current and the like, so when I say 'powerful' I just mean which headphone amp can drive the **** out of notoriously hard to drive 'phones like the K701 with the volume knob at about 9 'o' clock (ie. without even trying)?
 
Can I both money-no-object suggestions and reasonably priced suggestions. Is there even a budget headphone amp that is extremely powerful? Or a portable?
 
Preferably no valves.
 
Thanks for suggestions.

 

[hodgjy]

As far as "raw horsepower goes" (which is a bad analogy), tube OTL amps have the most.  They can handle the voltage demands of high impedance cans.  However, while OTL amps are better at voltage, they aren't the best at current.  Lower impedance cans really benefit from lots of current.  I think for the 701/2, you would benefit from a solid state amp with very high current.
 
For example, in the speaker field, you often see 4 ohm and 8 ohm speakers.  The majority of speakers are 8 ohm and the majority of big store bought amps are low current.  Coincidence?  These lower current amps really struggle to power 4 ohm speakers, despite them being lower resistance.  To power 4 ohm speakers, you need to look for the "high current" amps.
 
Same for cans.  The tough drive low impedance cans, like the 701/2, will be best served on high current solid state amp, whereas the high impedance cans (like the 600 ohm Beyers), will probably be best served on tube OTLs.

 

[Happy Camper]

Oops.

 

[MrSlim]

In the Cost is no object category, the Beta22 from AMB and the Dynahi from Kevin Gilmore (both DIY) are likely two of the most powerful solid state amps around. The Beta22 is capable of putting  out 18 Watts into an 8 ohm speaker load.  I'm sure the Dynahi is capable of similar power output.  They Hybrid EHHA (DIY again) is also capable of very high output current.  
 
From a bang for the buck perspective, the CTH (another hybrid) is amazing, capable of driving even Orthodynamic headphones, which except for the K1000, are probably the just about the most difficult headphones to drive properly.  I just sold one to someone who uses it with Smeggy's Thunderpants  (hand built headphones based on Fostex orthos) and loves it.

 

[nikongod]

Dont forget the dynomite amp. 
 
Krell used to (perhaps still does) demonstrate the silence of their BIG power amplifiers by hooking them up to Grado RS-1 headphones. 
 
1Kw monoblocks.... indeed.

 

[Avro_Arrow]

My Steve McCormack DNA .5 make a great head amp....

 

[Stereo Skunk]

As far as "raw horsepower goes" (which is a bad analogy), tube OTL amps have the most. They can handle the voltage demands of high impedance cans. However, while OTL amps are better at voltage, they aren't the best at current. Lower impedance cans really benefit from lots of current. I think for the 701/2, you would benefit from a solid state amp with very high current.

For example, in the speaker field, you often see 4 ohm and 8 ohm speakers. The majority of speakers are 8 ohm and the majority of big store bought amps are low current. Coincidence? These lower current amps really struggle to power 4 ohm speakers, despite them being lower resistance. To power 4 ohm speakers, you need to look for the "high current" amps.

Same for cans. The tough drive low impedance cans, like the 701/2, will be best served on high current solid state amp, whereas the high impedance cans (like the 600 ohm Beyers), will probably be best served on tube OTLs.

It seems like the only difference is the output transformer. Without much EE background, is there something the output transformer is doing to trade voltage for current.

As I type this, it kinda seems obvious. We step down from wall voltages using transformers all the time, and likely get a lot more current.

So is it, high impedance, leave the output transformer off, but with low impedance headphones using the output transformer helps with performance, but otherwise, upstream the amp is basically the same?

 

[sajunky]

Audio GD has a full range of class A headphone amplifiers starting from $315. A-2 is a new, the cheapest one, but very powerful 2.5W@25 Ohms.
http://www.audio-gd.com/Pro/Headphoneamp/A2/A2EN.htm

Then a single ended C2 3W@25 Ohms $450 and a balanced equivalent, well respected NFB1-AMP $485. Both have an expensive stepped attenuator, are built on a Master 9 design and can deliver maximum power 8W @ 40 Ohms.
http://www.audio-gd.com/Pro/Headphoneamp/NFB1AMP/NFB1AMPEN19.htm
http://www.audio-gd.com/Pro/Headphoneamp/C22015/C22015EN.htm

Going up with there is Master series Master 19, Master 9 and more. Very interesting is a new Precision 3 (2020 edition). It is a power amp 2x70W@8 Ohms, but can also work as a headphone amplifier delivering 15W@40 Ohms. The output stage is not a pure Class A, but very similar design in respect of eliminating crossover distortions. It can be bridgeable and bi-amped, but there is no on-board support, it requires special set of cables. I don't know, but a price $468 can be a mistake.
http://www.audio-gd.com/Pro/amp/Precision320/Precision320EN.htm

 

[Stereo Skunk]

Anyone know of a more powerful amp than rag 2?

 

[Stereo Skunk]

Found one. Violectric V280.

 

[Stereo Skunk]

Found another: ampsandsound Mogwai puts out serious power, too. It has an output transformer.

 

[ThanatosVI]

Bakoon Amp13R is certainly up there with 25w into 8ohm

it's one of the priciest but also one of the best to my knowledge

 

[techboy]

If all you’re looking for crazy volume:

You need to look at gain and not just output power.

Bravo Ocean has 30 dB gain. Never heard anything louder. I don’t think the Beta22 comes close in terms of sheer volume. I’ve heard both.

Project Ember 1 (not 2.1) is crazy loud too. A tad less than Bravo Ocean.

 

[Bonddam]

Well just talking power output isn't the Headtrip 2 at 50 watts at 8 ohms make it the most powerful headphone amp?

 

[havagr8da]

Are you planning on just strapping speakers on your head? Just kidding of course.