How does one copy cassette tapes to computer?

Another approach would be to purchase a separate interface unit that provides an analog-to-digital conversion function, and outputs the digital data via one of the standard computer-compatible digital interfaces (USB, Firewire, etc.). A vast number of such devices are available, at all kinds of price points:

http://www.bhphotovideo.com/c/search?Ns=p_PRICE_2|0&ci=14834&N=4294550051&srtclk=sort

I have no Mac experience, but in the PC world I would expect that one of these devices, if well chosen (be sure to review the user comments on any device being considered) would provide much better sound quality than a typical inexpensive consumer-oriented built-in sound card (or equivalent circuit on the computer's motherboard), in part because of inherent differences in their quality, and in part because of the proximity of the built-in card to digital noise in the computer. (I realize we are talking about cassettes, with their inherent quality limitations).

Rodman -- when you referred to the computer's "stereo mic input," didn't you mean the computer's "stereo line input," the mic input probably being too sensitive?

Learsfool -- On desktop PC's, at least, the stereo line input jack is color coded light blue, and will be located near the lime green line-out jack that is probably connected to the speakers. This is an example of the required adapter, if the built-in sound card approach is chosen.

Best regards,
-- Al

Also, if by any chance a digital recorder is available, such as those that record onto flash memory cards, another approach would be to record the output signals of the cassette deck onto that, and subsequently copy the digital file to the computer, either directly from the digital recorder, or from the memory card itself (via a memory card reader). Here are some digital recorders, again covering a very wide range of price points.

That approach would certainly eliminate the sonic degradations that might otherwise result in the captured file from computer-generated noise, although a good quality recorder will probably cost at least several hundred dollars.

Best regards,
-- Al

Rodman, thanks for the informative response.

What I was envisioning was the possibility that the mic input circuitry would be overloaded by a line-level signal before the signal information ever reached either the Windows software or the application software (Mixcraft in this case), unless the output level control on the cassette deck is turned down near the bottom of its range. But given your experience, and the fact that like your laptop Windows-based laptops commonly just have what is labelled as a mic input, and not a separate line-level input, I suspect that the gain and overload points of those inputs are not too different than those of the line-level inputs of separate audio components. I believe that the cheap electret mics which are commonly used with those inputs provide considerably higher output levels than most high quality mics, which would seem consistent with that suspicion.

A pet peeve I've had for some time is the lack of meaningful specifications for the analog audio ports on computers and computer sound cards, which generally makes it impossible to predict things like gain, level, and impedance mismatches with certainty.

Thanks again. Regards,
-- Al