You should be able to connect the Squeezebox to the tape in connection (and the Cd to the other input).
The question is - why would you want to connect an equaliser?
I was disappointed with the sound of my Squeezebox Duet when I first got it (it sounded rather dull compared to my CD player and turntable). I bought an external DAC and it improved it to the point where I no longer bother listening to CDs or vinyl anymore - the Squeezebox is much more convenient and sounds at least as good as the CD player.
