No no, not a deep notch... overall tonal balance is quite smooth bottom to top. No annoying frequency irregularity.
Really depending on the recording and the source and amp, but I would say, it is the clear type of midrange or vocal. For example, playing David Roth - More Pearls from Stockfisch Records, David voice sounds natural and clear... it is closer to reality, like you hear people speaking of singing in front of you. Good clarity and natural, with no emphasize on the mids body that with some other iems would make the vocal sounds thicker, warmer and intimate, not that type. Vocal sounds clear and natural to me, maybe a bit recessed compared to warmer sounding IEM.
For example comparing to Yamaha EPH-100, EPH-100 is darker sounding, also smooth, and for vocal, I think many people like the way EPH-100 emphasize the mids, it sounds fuller, warmer, and more intimate. With FXD80 you get more natural and clearer mids. So it is depend on what you like. Especially for Stockfisch recordings which I like, EPH-100 sounds warmer and nicer, softer treble. While FXD80 sounds clearer with more sparkling treble, and also better bass, it extends lower than EPH-100.
But for classical recordings, instrumental, Jazz like Jazz at the Pawnshop, it is hard to beat FXD80. Spacious, Airy, full and extended bass, good clarity, pin point imaging. No midrange issue with those kind of recording.
If you're familiar with Shure IEMs house sound, those 535 and lower (below 846 models), FXD80 is rather the opposite. Most of the Shures are rather dominant on the midrange, FXD80 sounds more extended on the bass and treble, and in comparison to the Shures, the midrange might sounds recessed. But not up to the extend that the recessed midrange sounds unnatural, but to the extend that the overall sounds signature sounds clearer, very good clarity, and very good bass. Midrange, I would say clear and natural.
Pairing also important. I recommend player or source that is a bit to the warmer or darker side of sound signature. For example, Fiio X3 is a good match with FXD80, also good with iPod, while with Audioquest Dragonfly DAC for example, the clarity sometime can be a bit too emphasized for some recording. Still good for classical and instrumental, but not for my Stockfisch collections. Playing Stockfisch through Dragonfly, I prefer Yamaha EPH-100 (or my Sennheiser Amperior).
I hope it helps.
fantastic thank you, i hope to give me my impressions soon, i probably will not burn them in to be totally honest (if i do maybe 100 hours ) not the 500 hours that some are mentioning here. i dunno why but i feel like the for dynamic drivers anyway " they can only be played a certain # of hours and the more i burn it the short its "lifespan" therefore i feel like it would short out quicker"-- plus i never listen to my music over 45-50% on on my iems and burning in seems like ppl are putting them at liek 60-70%
it would cause too much stress on the drivers i feel and short them out
probably just my irrational fear but regardless 500 hours is really long (i'm probably home maybe 12 hours a day +sleep) thats 41 days of burning them in