[LAU] checking passive input frequencies on non Hi-Z connection

ahoy all, i have been testing out a Zoom H5 which (along w/ the H6 for that matter) is advertised as NOT supporting passive instrument connections on the TRS inputs. to quote the manual: "Direct input of passive guitars and basses is not supported." thus i assumed that i would need a DI box/effect box/etc. to record well any directly connected passive electric guitar or bass. however, when i connect my electric guitar (Lace Sensors and Alumitone pickups) and electric bass, both passive, to the TRS connections on inputs 1 & 2 of the H5 with gain only at 5 of 10, i get a good sound and strong signal, seemingly the same as when they are connected to an interface (in this case a Zoom U-44) that supports Hi-Z connections. i first contacted Zoom support and they replied: "There is no issue connecting a passive guitar to the 1/4" input on the H5. There may only be an issue with level or noise, but if you are satisfied with the audio quality then there is no problem." now while i do not yet have a good understanding of Lo vs. Hi-Z, i have read various posts about it. they seem to indicate that the passive guitar signal would lose some frequencies with this kind of connection and thus this setup is undesirable. but again as it "sounds the same", i had some questions before investing in a DI box or getting a different interface: would the fact that the pickups are Lace Sensors and Alumintones have anything to do with the passive signal being picked up fairly well by the non Hi-Z input? is there a way to check (preferably in software) if frequencies are actually missing or if the signal quality is indeed reduced when compared to one from a Hi-Z input? is it possible that the H5 has good enough preamps/whatever that the gain on the inputs is enough to make the passive signal OK? so to summarize: is this an acceptable solution for recording a directly connected passive instrument (in this case an electric guitar and bass) even though the H5 does not officially support it? thanks, w PS: for those wondering the H5 works great w/ GNU+Linux as an audio interface