Get this one: http://www.amazon.com/gp/product/B00...7CPYJNSRKA4IWK
The Behringer 1002
unit is excellent, and under $100.
This is easy, really. You have 3 EQs -- high, medium, and low tones.
- You usually leave low alone.
- Slightly adjust high down. Hiss is in high frequencies.
- Slightly adjust the mid up, to compensate for the "lost" high (which was mostly hiss).
Using mixer hardware is not as good as software-only restoration, but it helps the software method by pre-processing the audio.
Though sometimes, you can get away with a pure hardware method. That's best for DVD recorder workflows.
Other restorations need the mixer, because the audio is so distorted and fubar, that capturing it would actually make it worse. Like good VCRs (though not used 100% of the time like the VCRs), some things are best fixed analog, before digitizing it.
That's all there is to it.