Certain frequencies hurt

Not an expert but your headphones are probably enough load to keep your transformers from being damaged but I'm not sure.   The Senns are listed a 300 ohm which is kindo high.  The Hifiman are 50 ohm which should keep your amp happy.

I'd be trying to figure out why my system is so harsh.

What are you feeding it with?  Many DACs and preAmps are also a headphone amp which would make more sense.  Your amp is heating up the room with 300+ watts of power to drive a load that a preamp can drive.

Jerry

How are you connecting the headphones to the Ref 75? 

Here’s my system.

Computer with Signalyst HQ Player

Denafrips Terminator Plus DAC (No HP access) Got this a few months ago. Before this had T+A DAC8 DSD. (No harshness)

Audio Research SP 20 Preamp (has HP access sounds good but with a bit of sibilance)

Audio Research Ref 76 Power Amp

(Headphones run through speaker taps with a WyWires connector which sounds sublime). Can’t load a picture but the connector is basically a 4 prong XLR on one end with 4 female speaker tap inserts on the other end-2 left, 2 right).

The volume set for the Senn HP’s is around 3 and for the Hifiman HP’s is around 13.

The ARC power amp is newly acquired. I thought there would be better synergy after I started hearing the harshness with my solid state power amp (Primare A32). But the SS had been sounding very fine. The other new acquirements have been power cords (2 Silnote and 2 Wywires) which I got a few months ago. Before that I was using some 10 gauge generic power cords bought from Amazon without problem.

I think it's odd the title is about frequencies that hurt your ears and then we are talking about Sennheisers.

Maybe we should talk about what causes your ears to hurt and how to correct that?

I'm open to suggestions. The ears hurt when listening to certain frequencies thru my speakers so my solution was headphones, since they don't hurt. Like I said I've changed out power cords, DAC and power amp all in the last few months. Wouldn't think the upgrades would be the culprit but who knows. The pain doesn't just occur with my stereo speakers, it's also with TV and car speakers (hence the HP solution). Not necessarily high frequencies but possibly high mids. Some piano notes are particularly disturbing. Can't even limit it to female voices, some higher male voices also cause pain.

Have you been to an ENT and an Audiologist? (serious question)

This is called recruitment  where the vestibular cochlear nerve tries to fire more nerve fibers and overshoot you probably have some hearing loss in those frequencies. Go to a ear nose and throat doctor and get an audiogram have them look at your ear drums to make sure they r ok

Haven't been to an audiologist in decades. I'll make an appointment. Thanks. Weird though, that the pain doesn't occur with headphones.

Unless you are listening at head-banging volumes, if your ears hurt something's wrong.  Go and see an ENT specialist right away..

In another thread there is a post about a (very costly) sub-woofer that can deliver 1Hz at 130dB.  Now that would hurt!.

If your hears hurt, it's time to replace your speakers that are more ear friendly.

Changing power cords to fix a medical problem is perhaps the most on-brand thing I've ever read on Audiogon.

@mewsickbuff 

what speakers are you using? How many hours on them? What tubes and how many hours on them in the Ref 76? The SP20 should not give you any sibilance.  What tubes are you running in the SP20?  How many hours on them?  Did you say your ears were hurting before you bought the new ARC amp? 

@ erik_squires I did not change power cords to "fix" my ears hurting. The ears started hurting "after" installing new power cords. I got upgraditis and thought changing the generic power cords for "better ones" would increase SQ. The solid state amp started sounding a bit more etchy after that change so I thought switching it out for another Audio Research component would improve the synergy. @ curiousjim I built a pair of OB speakers about a year ago with an increase in the amount of microdetails. No hurting ears. Prior speakers were Monitor Audio Gold 300's. No pain. The SP 20 only has mild sibilance when I use the headphone jack with the Senn 800's, none when I connect any headphones through the Ref 75 power amp speaker taps. The SP 20 is running 6H30Pi tubes with around 550 hours. The Ref 75 came with KT120 output and 6H30 tubes for the input stage. I was told they had about 200 hours on them. Listening volumes are between 65 -78dB. Softer volumes, no pain at all. Even if I hit 80dB it's only certain frequencies that hurt, not everything. There are some pics of my system on virtual systems. Haven't updated the power amp pic yet.

Hyperacusis. Possibly just coincidence with the cables.

https://www.leightons.co.uk/blog/hearing-care/sensitive-to-noise-misophonia-and-hyperacusis-explained

https://www.webmd.com/brain/sound-sensitivity-hyperacusis