Remember the mix tape? I remember it fondly. It was a true artform that not just anyone was willing to take the time and care (or the knowledge) to make sound good. Today, it's very easy. Copy all the files you want and create a playlist. There is no artistry in the process anymore.
The mixtape eventually involved to the mix CD, which followed the same concept but on the new medium versus cassette. But today. the most involved someone gets with making a "mixtape" is fixing the ID3 Tag and embedding cover art, which is pretty easy to find via a quick Google search. It takes nearly zero time and requires virtually zero effort and knowledge.
In the heyday of analog recording, you needed to at least have the skill to synchronize the play button on the source machine and record button on the destination deck. Usually, you'd have to start the recorder just a tad earlier than the playback device since there was always a slight delay on the recorder. I made sure that between songs, there was a three-second gap so the auto search function on the tape deck could recognize track gaps properly.
Beyond that, I remember looking for the peak loudness of every single song that's about to be recorded to ensure the least amount of hiss on the destination tape. And this is where thing gets a whole lot more interesting.
I used many outboard sound processors to make my mixtapes sound customized for my listening system. I used a SHM Project "Novar" noise reduction unit to eliminate noise from the source material, a BBE "Sonic Maximizer" to open up the high frequencies, a Carver "Digital Time Lens" to tame the harshness of early digital recordings, Carver "Sonic Holography" (shown) to widen the stereo spread by reducing crosstalk between speakers, and a Hughes "Sound Retrieval System" to create the surround sound illusion of two channel sources.
All of the above worked really well if you knew how to use them. And how do I know how to use them and which order I should put them in along the chain? Lots of trial and error. The only drawback? Even if you know exactly what you're doing, creating a good mixtape is an arduous and time-consuming endeavour. My personal best was spending two minutes for each minute of song, which meant mixtape album of 60 minutes (for a cassette) took two hours to do. And in the case of 80 minutes for minidisc (a dead format that I'm still using to this day) it would take 160 minutes to do as everything in real time.
Alas, with the proliferation of digital audio, doing this is no longer a possibility, or at least a desire. There is no standalone digital sound processor for consumers, unless you want to deal with buying a PC-based multitrack recorder, buying effects plugins, which essentially requires that you have a workstation instead of audio equipment. The fun is no longer as most people these days are content with a "good-enough" playlist. But sharing a playlist with the love of your life? It doesn't have the same ring and romance to it than giving a well thought out mixtape like we used to back in the day.