I had both S55s and RL60s connected to my 5000 for several years.
Medogsfat: S55's would be my personal choice out of the two
And to be contrary, I preferred the RL60s as I found the S55s were to bass heavy for my taste.
I believe the S55s were engineered that way to appeal to the Japanese market, but I preferred the thinner European sound of the RL60s.
First B&O (1976) was a Beogram 1500 ... latest (2011) change has been to couple the BL11 with the BL6Ks *sounds superb*