500 tapes eh? You'll need perseverance!
Basically any one of a number of cassette decks would suit but the most important thing is condition. Compared to a cheap little player that works well,
a Nakamichi Dragon or a Tascam 122 with a worn out head or which chews tapes is a waste of time. A Tascam 122 may have seen a lot of work and need a good service before you let it anywhere near important tapes. If the 500 tapes are important, whatever machine you use should be in top condition.
Anyone who's serious about doing cassette transfers properly puts adjusting the tape head azimuth to the actual tape's magnetic alignment very high on the list. Best to do while listening in mono but transferring in stereo -if it's a stereo recording. Hint: aligning on audience applause is ideal. It's like a white noise source and is vicious on any slight misalignment. If you are trying to decode dolby or dbx tapes when the azimuth is significantly off, you are wasting your time. It will sound disgusting.
Adjusting azimuth is also a waste of time unless the play head is virtually unworn. Any significant groove in the head will impede adjusting for any angle outside of that wear groove.
I suspect the average person has been conned into thinking that apart from maybe having a good cassette brand and model, digital audio restoration software is the key. It isnt. Getting a good clean ANALOG transfer is the key. The real pro's know this but the message doesnt seem to have filtered through. For example, if azimuth is significantly off when transferring, NOTHING can digitally restore this, except maybe for left/right phase coherence. Noise reduction software is an "after the fact" process. Unless the information is there in the first place (ie: has actually got to the line out sockets on the deck) no software can do anything to retrieve what's no longer there.
I sometimes surf the net for "before and after" examples on audio restoration sites. They mostly should be showing the difference between proper and improper ANALOG transfers - before it's even reached the digital stage. Instead it seems an opportunity to demonstrate just how poorly they understand the limits of their own software, or of their ability to use it.
Top drawer digitally remastered albums generally sound so good because all was done properly at every point in the signal chain, but especially the analog. "Digital remastering" mostly sounds better than the vinyl pressing because it eliminates the intermediate analog stages and gives you closer access to the original analog tape. That's why the CD cover makes a big thing about "remastered from the original analog tape". But it's also possible to digitally remaster from the original tape and do it badly.
Cassettes are no different except they're MORE fussy, both at the recording and at the playback stage, especially since they were usually recorded by amateurs. When some professionals refuse to work with cassettes is that because the sound quality is beneath them or the challenge of working so fastidiously is above them? Working with cassettes is a bit like playing a few chords on the guitar. It's easy - or easy to do it badly.
Oh and a good sound card is a must too. No fancy software can compensate for poor A/D conversion.
All the best, Tim
I think they thought it was a toy keyboard becuase of its size