@xcool a few questions for ya, if known. Agree with others, give it a lot more time.
1) what 6SN7 tubes came with it (EH?)
2) and, the 10 Mundorf caps were installed, correct?
3) How many hours do you have on the SLP-05 now before/after upgrades?
i.e. some years ago Cary use to run them for 2-3 days before sending them out. Not sure if they do that any more. Caps, transformers, tubes all settle in. I used to see people pulling the generic stock EH tubes in the 05 and using Popes instead, fwiw. Wondering what they sent ya.
Having used those same caps in three different upgrades (preamps and amps), let me share right up front the break-in and cap forming cycle can be "aggravating" to say the least, on those. Prepare for what we call "the rollercoaster ride" on those Mundorfs. I was warned too before my first try. It’s true. I emailed the Mundorf factory and they confirmed this for me while I was getting to be very impatient. Sounded bad new. Seems like it took forever. Finally got there. YES, the sound is going to change at 100 & 200hrs, some say up to ~300hrs. I heard changes even at 300hrs. No joke. I use the same caps in my (other brand) current monos. Mine sound different now, much more engaging, nice tone, texture, smoothness and more after the 200 and 300hr mark. Patience will pay off. Your experience may vary. I had to look again at the upgrade itself, link.