Also got a new PSU coming in today, fingers crossed there's a worthwhile difference over the iPower 1.0
So I ended up getting the LPS (Topping P50) to see how the Zen Stream scales after finding the iPower was a good upgrade but was still wanting
more.
My initial reaction was there was a further increase in impact on drums - this was after listening to the new Judas Priest album a dozen times so I was pretty used to how it sounded - first few minutes I was like 'whoa' and thought about turning down the bass (but opted to just leave everything untouched and get used to it). After that I felt it would be too hard to go back n forth so I lived with the P50 for a week before spending some time looking at them all.
Another thing I noticed right away was that my issue about vocals sounding too "recessed" or soft now was gone and everything was 'balanced' but crystal clear. My previous fix was to find a sharper sounding filter on my DAC, but now I dont need to worry about finding the right synergy and went back to my old settings. With the iPower I got the impression that vocals were either further back (softer) or undefined in location, more in between my ears than in front of me - the LPS solved that and were more obviously out in front of me with better texture as well, too.
The impact improvement was notable on a song like Traitors Gate (by Judas Priest, I was on a kick the past few weeks) where in the intro there's this drum line that goes from right to left and bouncing all over the place. With the LPS it was 3D and and really felt like those drums were jumping around the room, while with the SMPS it was more linear and less fun. For clarity, this didn't just affect the center stage but stereo details as well. On Hell Patrol, there's one guitar in each channel - with the LPS honestly they sounded like the same 1 guitar, but with the LPS it was obvious there was one guitarist on the left playing different things than the right, and the drums and vocals were all in a defined space. Same notes on As God Is My Witness, where on the SMPS I could barely make out what was going on with the left channel guitar (since they're playing the same notes with high gain) but with the upgrade I could differentiate the picking better. This also boosted the ability to hear other vocal tracks buried in the mix or off in the wings that I normally wouldn't notice until I throw it on vinyl w/ speakers.
Another thing that popped up on the Zen recently was noticing how sibilant S's are on tracks, and this is a big factor on the
Painkiller album. It got pretty annoying at times when the S's were resonating louder than any other sound, and I think that was smoothed a bit and nothing was annoying me anymore.
Anyhoo, one last test I did was checking out the David Lee Roth solo album since I remembered the vocals on the mastering being especially soft in the mix. Used Ladies Nite in Buffalo as my test track. With the SMPS I had trouble understanding some of his lyrics as gibberish with the volume I had set, but with the upgrade the words were clearer and I could actually type them out correctly. So wrap that in with the previous vocal notes.
disclaimer: these are minor changes at the end of the day, my first thought going back to the SMPS was "yeah this is still good" before digging into specific things
TLDR; The negatives I noticed with the previous SMPS upgrade were gone, and the Zen Stream benefits got better. Happy camper, endgame satisfied for now.