id say the corda rock looks just fine?
-> Bad frequency response, suspicious channel matching, high output impedance. Doesn't look fine to me.
hmmyes, i agree on the channel matching... but srsly 0.2db will never be heard. ppl tend to forget, what the actual frequency reproduction channel deviation on their headphones! is like (were talking 0.x to multiple dB), right?
frequency response might be "bad" as for measurements, but 0.5dB drop @15k max will not be audible aswell... if you do a blind test and proof to hear a difference between a filter according this FQR and no filter on an actual recording, id hire you for a studio
but i agree, its questionable whether a 250euro hpa should have a better FQR (at least perfectly flat in the audible range) or not... output impedance is 4Ohm and i would not call 4Ohm"high" at all... thats perfectly ok for 32Ohm headphones id say?
The Jazz actually has some nice features: perfectly flat FR in audible spectrum, low output impedance, a stepped attenuator volume with perfect channel balance. And if its output is 6 dB louder and cleaner than Amir meausured (due to ignoring the differential ground channel), it's not bad. This would have put it in "Class A" territory 20 years ago, similar to Tyll Hersten's old Headroom amps.
that is EXACTLY what i think... not mentioned the crossfeed. i use meiers crossfeed filter as VST plugin and i would NEVER ever want to loose it, many recordings sound so much better with it... if your using a CDP f.e. you need a DAC with DSP (and crossfeed function) otherwise, wich will be seriously expensive (question btw: are there any which do not cost a fortune?), or have that option build in with the meier audio amps (though, not variable, only on/off). the ifi audio hpas do some crossfeed aswell on the "3D" setting, right? in the end, the similarly priced micro iCAN does 400mW into 32Ohm, not 300mW like the jazz... well uhmm...
but honestly, the output power on jazz IS really subpar... 30mW into 300Ohm, i still cant believe that. i would not want to pair this with an average sensitive high impedance headphone... maybe a focal utopia would do just fine?
j/k