Many audio people preoccupied with a desire to reproduce what they feel might be a “full auditable range”. As a demonstration to themselves that this system are full-rage-able they pay a lot of attention to a reproduction of extreme frequencies: sub 35Hz and above 13kHz. The extreme frequencies are quite complex subject and 98% of audiophile while they pursue to the extreme frequencies they end up with extremely horrible results at those frequencies. However, they still would like to have those bad results for sake of having so-called “full range”.
The extreme frequencies are very complex for reproduction if you do not know what you do (98% of you do not) then do not reproduce the extremes at all. Ironically the playbacks that do not attempt that crappy reproduction of extremes sound way more interesting. The key is following: our consciousness easily reconstructs and re-enact missing information but it has much more difficulties to correct and to repair a recognized but wrong sound. There are a lot of complex inner-mechanisms that block out our appreciation of musical peace if a portion of out listening awareness dedicated to the rectification of crapy reproduced frequencies extreme.
So, if you do not know how to make the extreme to sound correct then do not do them at all. Your playback will not sound worth (musically) without extreme frequencies and it will sound better then your attempts to fake extremes by some artificial audio means.
"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche