I have an Eheim Pro II 2026 and it's SO quiet, I don't even know it's running. The only "problem" I had was the intake/outlet valve on the top of the filter cracked once, and I couldn't figure out why every time I plugged in my filter after cleaning it would start to leak. So I took it all apart and finally discovered that there was a hairline fracture in the plastic casing on the valve which was allowing water to escape every time it started to flow after priming. I ran right out and replaced that piece - I think it cost me about $15 but it was worth it, otherwise I would have bought a whole new filter, and Eheim filters are quite expensive. I thought it might be the O-ring on the inside of the filter, so I bought another one and when I replaced it, the filter continued to leak, and then I found the crack. I don't know how it got cracked because I'm usually very careful with the parts, and it happened when I was at home. Had it not, there could have been a lot of angry people in the apartment below me!
I love my Eheim... I'm so glad I did my homework before I bought an outside canister filter. It's been one of my best investments.