Despite the obsolescence of this format, I have a zillion old cassette tapes I'd probably like to listen to occasionally. Any recommendations for a top-quality affordable deck?
Top quality, affordable and new is a tough combination in this digital world. Most new cassette decks are not very good.
I don't know how you feel about buying used. There is a tremendous surplus of used decks in the marketplace (audiogon and ebay). Most used decks will require some service (belt replacements, recalibration, etc.) Some have been sitting idle for years in basements or attics. I think a deck should be maintained so that it is operating at its best. You may not want to spend the money.
Will you only be listening to old cassettes or will you also be recording? Are these cassettes prerecorded or did you record them on a deck?
Some brands to consider in the used marketplace: TEAC, harman/kardon.
If you can provide more details about your situation and/or have other questions, I will try to help.
I'll be listening to primarily to old cassettes that I've recorded myself, very few pre-recorded tapes. I might be doing some new recording, but probably not very much in the long term.
Used is okay, as long as the equipment is high quality and in excellent condition, requiring no professional servicing.
I've been scanning eBay and Audiogon for the Nakamichi Dragon, DR-2, etc... Do you have experience with those?
"Used is okay, as long as the equipment is high quality and in excellent condition, requiring no professional servicing."
If you buy a used high quality deck that is truly in tip-top shape, it will cost you a few bucks. Most decks, even those that are claimed to be "mint", require service. Many sellers are not entirely truthful.
I think that, for your intended usage, the higher end Nakamichi decks (e.g., ZX series, CR-7A, Dragon) are overkill. The only Nakamichi deck that I used is the DR-10, a last generation Nak that performed well but is not considered great by some authorities when compared to some earlier models. I can only say that it produced some fine recordings for me when using a high quality Type II blank. You might want to exclude Nakamichi decks from consideration for two reasons. I believe that Nakamichi uses an equalization that differs from other manufacturers and the head gap is narrower on Nakamichi decks. Thus, cassettes that are recorded on non-Nakamichi decks and played on Nakamichi decks (and vice-versa) will sometimes sound disappointing. I am not trying to steer you away from Nak decks; just posting some issues that some analog cassette fans have expressed. The magnitude of the sonic differences will surely vary and will be immaterial to some listeners.
Since you will be playing several old cassettes recorded on a different deck, you might consider a deck that features a play trim control, which would adjust for differences between the old and new decks and address other issues on the recorded cassette. After reading a bit about play trim, I am still not entirely clear about the feature. It seems a few different definitions exist. You might do a google search and investigate. The following link to an NAD manual which includes a description of one definition of play trim is informative: