Just a few hours of burn-in today – I don’t expect much change with Tesla-quality drivers etc. The treble is recessed almost as much as the Philips M1 I had, kind-of a worst-case scenario. So I took out my most minimal non-peaky non-bright non-sibilant headphone – the B&O H6, and even though it doesn’t sound the same as the T51p because of the H6’s “light” midrange, I wanted to get a sense of how much the T51p was recessed below a very minimal treble. My Foobar2000 settings were +2 at 2.5, +4 at 3.5, +2 at 5, +4 at 7, +6 at 10, 14, and 20 khz. Normally I wouldn’t do the dip at 5 khz, but the T51p has a nasty 10 db peak around 5 khz, which makes it difficult for portable use without a customizable equalizer. Without a treble boost it sounds very boomy as well as muffled. I can understand Beyer going to a darker sound with more bass – in fact I thought it was a move in the right direction. But they need to cut that (resonant?) peak around 5 khz. I compared to several other headphones and none of those were anything like that.
Earbuds have small speakers that rest on the ear canal of the wearer. These are usually much less expensive than on-ear and over-ear headphones and reproduce the sound well. However, outside sounds, such as traffic or power tools, can get past the earbuds and interfere with your enjoyment. Earbuds also don't stay in place very well if the wearer is moving much, such as exercising. These also are lower fidelity than on-ear and over-ear headphones.