Folks, if you have never tried this headphone on an Emotiva BasX A-100 in beast mode (jumpered headphone out) then you are truly missing out. It is not enough power for the T50RP Mk3 out of the box, but in 50W mode... oh man. It's amazing. Just wanted the world to know.
Back in the 70's Yamaha Orthodynamics were connected to a dedicated headphone output in the 125 Watt Yamaha receiver that would provide the 10Watt peak and 3 Watt /channel RMS power required to drive them.
The best kept secret is that the stock Fostex Tx0 RP MK III when connected directly to the speaker terminals of a
100+ Watt RMS per channel at 8 Ohms ( especially if this amp will deliver 300+ into 2 Ohms) it will blow away any and all headphones powered by headphone amplifiers that I have ever owned or borrowed.
This is because Orthos require lots of power and headroom to come to live and in addition orthos require "Constant Zero Output Impedance across the entire frequency spectrum" in order to come alive. Now if you power the Mr.Speakers Ether C flow with such an amp and then try the Senn 800S you will be wondering what happened to the huge sound stage of the Senns. Recently a lot of people are selling their Hifiman Edition X V2 because they think they can drive them with headphone amps.
This is because even at 100+ db/mW these headphones transform themselves to giants when powered by high powered low impedance speaker amps. Hifiman says not to use more than 2 Watts/channel amps to avoid damaging the drivers. Nothing is further from the truth the X V2 is still scaling up when driven by my AMC CVT 2100 (85W/ch RMS at 8ohms) as for my other orthos I went out and got me a Crown CE1000 rated at 275W RMS into 8 ohms and 560 into 2 ohms.
However when all my Orthos are driven by the AMC 2100 then the He-6, Mr Speaker Ether C Flow and the X V2 are clearly a class above the Fostex's. The Smeggy Thunderpants and the ZMF Purple heats are still easily superior to the MK III something that is not at all apparent when driven by headphone amps. Smeggy and ZMF are equals with different signatures you may use one or the other according to genre or mood.
It is also important to state that quite often I find myself reaching for the moded Fostex's as they seem to posses a more vintage sound. Not romantic like the He-6, but vintage (lots of tape, tube and transformer, saturation/compression artifacts)