Yes, I have actually. I really enjoyed the HD650, essentially the HD6XX, and tried it many times. Honestly, it depends on the sound you want and there are so many worthwhile reviewers that can give subjective impressions and objective data.
From my perspective, I liked the soundstage and treble of the HE4XX. It is a smooth and enjoyable headphone. The HD58X has more noticeable bass than the HE4XX and HD650, but it’s less noticeable compared to the HD650. The HD650 is smoother, I didn’t detect any grain in the treble, but I and some other users heard grain in the treble of the HD58X. We discussed it in another post. A YouTuber, Metal571, heard it too. The HD58X is a better critical listening headphone than the HD650, sans that grain. The 650 isn’t as “neutral” as the 58X, but the 58X isn’t that neutral either. All Sennheisers are vocal specialists, as you know, and they all excel at it with that respect- just with slight tweaks to tonality. I have no experience with your amp and haven’t seen any measurements. I only saw some specs and if the posted output specs are correct, your headphones will have enough power to be audibly loud- now where it clips or distorts, I do not know, so you might not get full power. So, I can’t give you any advice with respect to your upstream gear besides that. The HD58X is good for the price. A damn fine headphone. If you haven’t heard the HD6XX, and you can try the HD650 at a store, please do. My ears liked the HD650 more, even the HD600. The HD58X could be easily driven by low power amps, does scale better with better gear, but the HD650 scales even better with proper power because of its high impendance. Neither would be terrible choices, I liked them both, just couldn’t get over the slight graininess of the HD58X and liked the presentation of female vocals on the HD650 more, so I sold my HD58X. I ended up with the Focal Elex. I sold my HE4XX also and bought the darker LCD2C. Decided I missed the Hifiman sound and jumped on a Sundara. What does this mean? Definitely recognize what you like, what your current gear can do, what you want to upgrade, and the soundsignature of the HPs you have or want. Now, I use my Elex for critical listening and music production, LCD2C for leisure, and Sundara when I want a mix of both and a little more treble.
Some good review sites-
Audio Science Review
yes, even SBAF
my go-to Youtubers: