Ahhh...yeah... a cassette, regardless of pedigree, is by definition going to be inferior to its source (check the specs).
And yes, having worked in numerous studios (CHML, CKDS,CHMR and more) AND working for Retailers (almost ten years) who carried Nakamichi, TEAC and a wide variety of the rest (Technics, Luxman, B & O, Pioneer etc...) back in the 70's and eighties I had the opportunity to compare the various tape formats of "The Day". Open Reel tapes, especially, "Originals or commercial copies" are the best. Next, CD and Turntables (roughly even) and cassettes, being copies of the originals, are always my last choice (but great for portability).
This is not to say cassettes sound bad... just don't compare them to what you copied, on a highly resolving stereo... it may lead to cognitive dissidence :(