Denafrips Iris vs ifi spdif ipurifier 2

It is dependent on your preference, and if you want to try a DAC maybe ask iFi as to what is a good match, they have a lot of dacs and probably have a sense for what matches your setup.

It's difficult to answer your question, but I bought an iFi SPDIF iPurifier 2 when I had an old Revox CD player from 1990 used as a transport knowing that it would most likely really benefit from it. And indeed it did - and it did even more when I replaced the iFi wall wart with a 35$ 5V low noise linear PSU from AliExpress, fed through a filtered power strip.

Last June I bought a modern transport (Audiolab 6000CDT) and, according to some, the iFi iPurifier wouldn't be needed anymore, modern DAC + modern transport... yet I find everything sounds better with the iPurifier in place. YMMV, as always, but it costs nothing to try since you already own it, and I doubt it can be detrimental...

I found the gustard u18 which does the same thing as the denafrips, plus it's returnable. I'm going to test it out to see if I get any improvements. If denafrips had free returns I would have tried that. We'll see what happens. 

since you own the SPDIF IPURIFIER, 

just go for iFi flagship iPower Elite to pair with iPurifier.