That would still make it without value. Your short-term “echoic” memory only lasts few seconds, not hours. And as differences get smaller, even a fraction of a second is too long to remember minute differences. But even if you had used short-term AB testing, unless you match levels and perform the test blind and repeated, the results are without value.
I implore you to do the test again but properly. You can buy DACs with much better performance than Mytek for as low as $100. Be sure to match both levels and do the test blind. Repeat 10 times and see if you can tell them apart at least 8 times. This is how to do the test properly and without bias.
Without this any of us can come up with your outcome, or the reverse. I know, because I have done it.