I agree with the Lord.
The 640 and 650 need slight 'modifying' to get the 10x5 to work properly. I for one am not a great fan of the 640p no matter what anyone says. I used one for a while (no thanks to the over rated reviews) and found it to be VERY limited in what you can and can't use, and what it can and can't do. If looking for an upgrade on a 'standard' internal MM stage that is found inside an integrated then the 640p is very good and great value for sub-£100 BUT and it's a great bit BUT, if you are looking for something better that will get more out of your setup then look elsewhere. The P75 will do a MUCH better job as will the Rotel. The P75 has the advantage of being able to offer the 10x5 a more 'precise environment' and is better sounding to boot. Given your £200 budget I would have looked at the P75 instead of spending £60 on a starter phono stage.
Hope it's better than the X-LP, that was possibly the worst and most boring phono stage I ever heard.
If the Cambridge sounds better, then stick with it. If you want real and significant improvement however then look to something like the Dynavector that you can match exactly to the rather unique demands of your cart.
Sorry Nando, compared to a Graham Slee, a Dynavector, the Whest, the budget Pro-ject, the internal phono stage on a Naim 62, and the Loricraft, it was boring. Maybe the X-LPS is a different beast.
TBH we'd need to know more about your system, what is it, and what sort of Music do you like?
You could try something like a Naim 32/140 combo, the phono's really good in that, it will mate beautifully with the Ela's, and will certainly be an upgrade from the Rotel. Just a thought.....