Cayin 50t and capacitor suggestions

I am thinking about doing a capacitor upgrade for this amp. I currently have mullard re-issue el34s, nos amprex 12ax7s and 12au7s. I like the sound quite a bit. I would, however, like more inner detail. I wonder if others have modified this amp with coupling cap (.22uf) upgrades and liked the results as far a detail. I'm also considering selling it and upgrading to another unit. The rest of my system is: welltempered clasic, bottlehead suduction, cary 303 cd player, energy veritas 2.3 speakers (90 db).
For coupling caps I have used both Mundorf silver and oil as well as their silver/gold and oil. Very happy with both. For two caps the gold is fine beyond that it costs too much and the silver comes into play. For power supply I like ruby gold