newbie seeking advise on Quad 606 caps

Hi all,
I am newbie here..
I recently got a QUAD 606mk1. I saw from its schematic and compared with 909...Some ppl reckon to change C7, C9 and C11 to better caps....

Beside that, can I change 606 C3 cap rated 680nf to 909 C3 cap rated 1uf film cap, say Auricap 1uf 400V? Is it advisible to do so?

Many thanks!

1.Can I use PP cap like Mcap or Aricap in C7?
2.Eh...sorry for this metallized polypropylene cap = PP cap = Film cap? :confused: