I have listened to the unit with and without the PSU and the difference is pretty big. I would get the PSU if I were you.
I am using the buffer in a different way. I have a 47 labs shigaraki dac & of course it has no active output or digital
filter on the dac chip but simply uses a resister network.
I wandered if the mf buffer would help prevent the dac from
being loaded down causing frequency abberations and also maybe
extend the bass a bit. But I worried that some of the analog-like transparency would be lost. Well so far it seems
mostly an improvement in linearity with a slightly more easy
presentation of highs such as soprano voice and the bass seems
less rolled off (into tube preamp-6sn7's). I do think there is a very slight loss of transparency which so far has not
bothered me. Someday I'll switch back & compare. I too wandered if the psu would be a good upgrade. I also wandered
if a diy pwr spply frm welbornelabs would be better for less?