I've gotten the most noticable differences in system sound based on (descending order of magnitude)
Speakers/Headphones
Room (for stereo listening)
DAC/Cartridge
Subwoofer placement/integration
Phono stage
Amplifier (tube types)
Preamplifier (with/without tube type)
Streamer
I haven't done DSP but do have a DIRAC unit collecting dust and based on what others say it could fall somewhere between subwoofer integration and amplifier.