Where did you buy them? $80.00 is very cheap for these. There have been fakes of these iems circulating, have you probably purchased a fake? I don't own these but I have owned a few iems fron senn (mainly their older line up) ie7 and ie80. As for both, Although they have a rather thick low end, they were never thin, if anything they were lush (too lush for the case of the ie80). I would also like to add, what source did you drive them with?

$80 is the going price all over the internet including the Sennheiser web site

https://en-us.sennheiser.com/ie40pro

I'm actually baffled because I was expected to hear a even handed IEM. But I can't 'imagine' bass where there is none -or- tell myself I don't hear what I know I hear. Or don't hear in this case...ie anything below upper midrange.

How about the source you drove them with?

Fiio M11, compared them to the Shure SE215. The Shure's have bass, its night and day.

Sorry they didn’t work out for you, thanks for giving them a try!

Same exact problem. Called support. Answer was "they're monitoring headphones so they'll sound different" ... I asked three times "You mean zero bass, barely any mids? Why would you, anyone, make headphones were you literally can't hear half of any song?" The reply was "Sir, they're not intended for consumer audio ... they're for stage monitoring."

?.. don't people on stage want to hear the range of sounds? ... WEBSITE DESCRIPTION - " ... the advanced driver system brings a considerably expanded sound spectrum to the ears of musicians, sound engineers and DJs." Right. Duh. All manner of music.

Frequency response
20 - 18,000 Hz

So clearly there's something wrong with this set ,,, or batch ... but for a Sennheiser rep to try to excuse it as nothing is wrong? ... wow ... that speaks for itself and perhaps explains why the hold times for support and customer service are long ... too many calls?

It was something wrong with batch.....I sent mine back, they replaced them which took about a month. The replacements sound good, they are pretty flat

I ordered one from wish for $40 USD. When I received them I thought they were a counterfeit so I asked for a refund. Company gave me the refund and told me to keep the headphones. Still, I wanted the ie40 Pro, so I ordered them again, this time in Amazon from Senheiser. Well I got them and it was exactly the same headphone... Same sound same build same box, same everything. Back they went to Amazon. I think Senheiser has a big problem with counterfeits...

I listened to one from Ebay for 50€, sounded funny. Not great at all. I bought one from Amazon later on and it was a real one. No comparison possible.Very good. And yes, it has bass and even good sub-bass. Crystal clear treble and good timbre and great mids, just a little bit recessed. Very clean sounding. Very happy with them.