I have had several Naks, CR-1a, CR-3, BX-300 and Cassette Deck 1 Special Edition (silver).
I would not worry about the tapes giving you problems with playback in your walkman or car. I have a pretty good walkman I paid well over $100 for back in 1998 (silver aluminum body) and tapes made on my NAK deck do not sound muddy or in any way indistinct on the walkman. These tapes sound fine in my car as well. Where they do not sound as good as playback on a NAK deck are on some other home and pro decks... on a Denon, Marantz, Teac, the tapes do sound rolled off in the highs but still have good bass. I typically record tapes on my BX-300 on my downstairs system and then play them back on my Cass. Deck 1 on my upstairs system and the tapes sound great. BTW if you can find any Nak. brand tapes these are the bomb and the best tapes I've ever used.
I would not worry about the tapes giving you problems with playback in your walkman or car. I have a pretty good walkman I paid well over $100 for back in 1998 (silver aluminum body) and tapes made on my NAK deck do not sound muddy or in any way indistinct on the walkman. These tapes sound fine in my car as well. Where they do not sound as good as playback on a NAK deck are on some other home and pro decks... on a Denon, Marantz, Teac, the tapes do sound rolled off in the highs but still have good bass. I typically record tapes on my BX-300 on my downstairs system and then play them back on my Cass. Deck 1 on my upstairs system and the tapes sound great. BTW if you can find any Nak. brand tapes these are the bomb and the best tapes I've ever used.