Good cassette player?

Try to find the same model deck you recorded them on (in good operating condition) and use single ended IC's as already mentioned.

Otherwise just send them to a transfer service (T/F to CD and/or a memory stick).

DeKay

I remember much better treble extension in AIWA deck equipped with HX-Pro (bias servo), but it was only for recording.

some nice refurbished Nakamichi sometimes available at decent prices....you might want to make sure the tapes are still good before you spend money...sometimes they decay badly, physically and sonically...

Save your money. Most likely these cassettes are not usable anymore. I hate to be the bearer of bad news, sorry. 

Dear @clustrocasual  : This one is a VERTY FINE DESIGN AND YOU CAN FIND OUT SECOND HAND PROBABLY THROUGH EBAY, page 58:

https://worldradiohistory.com/Archive-All-Audio/Archive-Audio/80s/Audio-1984-09.pdf

Regards and enjoy the MUSIC NOT DISTORTIONS,

R.