I think you've really got to decide in the first instance if you can afford/ would be prepared to spend the amount of money between the two pre-amps.
No need to listen to the 552 if the answer to the first question is negative.
If yes, then you should borrow a used / broken in example and hear it at home and compare with the 52. You may be surprised and not notice a whole heck of a difference or, you may hear night and day difference.
Not all of us have super hearing or listen to music intensely. More often than not I fall into this camp. When I changed from 252 to 552 I heard an improvement but I wasn't left mouth agape at how things had changed. It's still a stereo and the bands remain in the concert hall, not my listening room!
This seems sound advice to me. I haven't heard the 552, but a parallel might be when I bought the Dave DAC - there is no way I would have listened to it if there was no possibility of affording it at least in the reasonably forseeable future. And when I did hear it, to me the improvement was so significant that anything less would have left me with knowledge that what I had was lacking.
But hand on heart, can I say that I get more enjoyment or pleasure listening to music through my present system, with new value approaching £30k, or my first system that cost me the equivalent of maybe 1/30th the amount (£60 in 1969, albeit with quite a bit of DIY), with its inherent rumble, wallowy bass and muffled treble? The answer is no: I think the enjoyment and pleasure playing music now is probably the same as then, though I hear more of the music now, with greater realism.