Does a graphic equalizer show where your amp is lacking?

 I am a fringe relatively unknowledgeable audiophile. I purchased a year ago on  Audiogon both a Technics SUG700 integrated amp and Canton 9k reference speakers with shaker cables, my source is a Marantz CD player all interconnects are 35-year-old monster cable. It is a very revealing system. Having said that I recently purchased a Schiits Loki equalizer and was surprised at the amount of added detail it provided to the music most noticeable in the higher frequencies i.e. violins have more sparkle and inner detail.  My question does this mean the sug700 is lacking in that regard.Also since the Loki alters the sound is this like having different speakers simply by altering the sound signature of the Cantons by boosting or suppressing its various frequencies? What is the downside to equalizers other than adding another piece of gear the signal travels through?

As an aside I read a post on here about Chinese knock-off audio goods so for the fun of it my price of admission was around $20 for a pair of knock-off Van din Hull interconnects normally costing a few hundred bucks. Well, I got what I expected JUNK wrapped in a Van din Hull cover. It played ok until I turned up the volume when my amp told me "signal overflow" whatever that means( clipping ?). Anyway removed the ripoff and attached my old Monster interconnects and no more signal overflow just sweet music. If these were the real deal they are defective as evident when taking it apart, just sloppy workmanship! One example the center pin on one RCA interconnect was not only poorly coated but half of one pin was cut through! The copper strands were sloppily crimped with many strands not where they should be  and no soldered connections just press fit.