The cheapest dacs that would have problems would probably be off-brand portable players from the mid-90s. Dacs are a lot better these days and software masks many sins.
Current iPod lineups have decent dacs as you suggest, but the old white “gum-stick” iPod shuffle’s have some of the worst dacs and analog circuitry I’ve ever heard… noticably different than current iPods and iPhones (most iPhones are pretty good).