k110 ~ 60Hz - 8000Hz(8Khz)
k120 ~ 50Hz - 6000Hz(6Khz)
the other side of the graph would be in Db's, and with the K, E and D series is pretty linear throughout it's frequency response.
from a guitar standpoint the k110's are decent with the fundamental frequencies of the guitar as is the K120. however the higher harmonic content, and/or air will be passed 2000Hz(2Khz) more with the K110 then the K120. pretty noticeable diference in this area. that is why you hear the term Hi-Fi related to the K110. Looking at the Bass side of the frequencies of the k110 and you will see 10Hz less then the k120. while that is not too substantial when looking at the fundamental frequencies of the guitar, it does lack those 10Hz that an effect like the boss oc2 will definately fall into using.
Disclaimer: I make and sell Buffers. I also sometimes Modify, Build and sell preamps and amplifiers. My opinions are not intended to be sales pitches. I am a one man shop and prefer to spend time with my wife and family, i work full time on call and love to spend my spare time doing other things. I only make, modify or build things for those that seek them.