I don't try cheap amps and dacs so I can't say (because I just try for fun and am not shopping), but on the higher end, the signature and quality of the dac/amp can overpower the qualities of the headphones very easily. I'm not saying amps and dacs HAVE TO make a difference, or that they make a positive difference, but they CAN make a massive impact on sound

I don't use amps, dacs, or headphones because I only use a portable setup