Is there no difference between the 9018 and the 9038?
There are usually measurable differences but there is RARELY ANY audible defects/or difference with a DAC (in a proper, blind, level-matched
ABX Test). If there is a difference it's usually noise (hum, hiss, or whine in the background) but that's coming from the analog electronics or it's getting-into the analog side from the power supply. It's not the DAC chip.
You'll read all kinds of flowery nonsense "audiophile" descriptions of sound, and that's usually because they "don't believe in" blind listening tests. The flowery language is a big red flag. If they aren't talking about real characteristics like noise, distortion, or frequency response, I'd ignore what you read.
...I don't own a separate DAC. There's a DAC built-into my computers, my AVR, my TV, etc. (I had a computer once with a noisy soundcard. I could hear noise through the speakers/headphones when the hard drive was accessed.)