Tube Amp, Preamp upgrades -- what did you do that improved your units?

@hilde45 Did you ever complete your QS cap upgrades? Reading this thread its not clear which QS model you are working with. If you have a newer QS item I do believe the capacitors if white in color are already Film and Foils if you replace these with any kind or metalized polypropylene cap you're most likely doing a down grade. In almost all cases a film and foil cap will be sonicly superior to a MP regardless. Mike at QS now has available on the QS website Film & Foil capacitors to replace common QS sizes .27uf, 2.0uf, and .056uf I believe. If yours are yellow in color or not identical to the new QS caps you should consider the QS labled film and foils. Im currently updated an older QS full function preamp that seems to be using older QS Metalized Polypropylene caps. I will be using the newer white film and foils from QS. You can view my progress on lowpower audio on youtube.

@hi2alex2 Yes, all upgrades are completed. Amp and preamp sound improved to my ears.

This is an old thread but grannyring, if you see this, I am interested in thoughts about upgrading my Quicksilver v4 amps. They are the earlier transformer models but I use KT-150 tubes. I love it but wonder what might make it even better. It was upgraded with mundorf supreme caps before I bought it.

I have a Berning tube preamp and the v4 feeds Verity Parsifal encores and a six pack of REL G2 subs 

Thanks for thoughts!

FYI, the QS model is Mono 60.

The upgrades:

• 2 Quicksilver White Caps (.27uf 400 VDC 1543R) were replaced with (a) a Mundorf 2uF 1000Vdc MCap® Supreme EVO SilverGold Black SESG and (b) a parallel “bypass” that added an Audience/Auricap cap (0.047uF 400Vdc XO Series).
• and, 
• 2 Orange drop caps were replaced with 2 Mundorf Cap 0.22uF 1000Vdc MCap® Supreme EVO SilverGold Black SESG.

The sound improved.