Ok, so the Performer 5 arrived and I already have some thoughts.
I love the shell. It's small and fits comfortably flush in my ear. Definitely an IEM you can take to bed. I have no opinion on the faceplate. Not my style, no idea what it's supposed to represent. If this IEM were more expensive, I would like to see recessed sockets, a tighter woven cable and a cerumen filter on the nozzle. But considering the price, I have no cons.
Regarding sound, it's a quite bassy IEM - much more than what I would normally listen to. But it's ok, I can dig it. Works great at low volume and when you need some extra oomph. Treble seems reasonably smooth with one exception. Above 10kHz it's too much. It sometimes sounds like if the seal is broken but I think that's actually from the IEM and it can sound quite bright. It's not a deal-breaker at all, though.
If there's a flaw, it's the midrange. The vocal presence is softened a bit (broadly at 3 kHz) but the 2 kHz sound a bit too prominent. What I actually noticed when using a sine tone generator was that 2 kHz sounded weird in general. Like if a lighter tone is playing at the same time. THD hits 0.8% but that's totally fine and could not be what I'm hearing. So I noticed a small phase shift exactly around that area. There must be a crossover and it's not the smoothest ever.
But again, all things considered, for the price it's totally fine.
With a v-shaped tuning, I'd expect a wide and deep soundstage. That's maybe the biggest let-down for me. Everything sounds very in-your-head and there is hardly any depth at all. Actually, the P5 struggles to pull instruments apart and it all sounds wishy-washy to me. Transients lack attack and speed, imo. But then again, I usually hear music with far more expensive IEM, headphones, speakers, ... So, again, no complaints!
Timbre falls victim to the tuning. Male voices sound thick and female voices are either dark or bright depending on their vocal range. It's not dramatic at all and it just makes the music sound more dynamic. Could you mix on these? Definitely not! Are they fun? Yeah.
Everything is fine, I don't regret the purchase. I will use the P5 for YouTube, badly mastered audio and bed time listening. It's far more comfortable than RSV or Cerberus, which I also have next to my bed.
Edit 2:
Correct measurements added. ADI-2/4 Pro 4.4mm out, IEM mode, SD sharp, no B/T / EQ / Loudness. SPL matched at 1kHz 90 dB. More here: https://www.klauseulenbach.de/iem-frequency-response/