There are people who will sell you a volume knob, machined from specially selected wood with exactly the right qualities, which will attenuate harmful resonances or otherwise purify the music you’re listening to. Others will sell you gold-plated SPDIF optical cables, or oxygen-free Ethernet cables which give the audio you’re streaming a warmer, fuller, more alive sound or something (presumably the expensively sourced copper in the cables somehow flips the bits in packets containing audio so that the audio the DAC reconstructs from the data is more aesthetically fulfilling). And if you’re a true ‘phile, you can pay the electric company to replace the transformer your house is connected to with one that delivers electricity with superior acoustic properties.