I did some extensive listening tests with about 15 different capacitors in the signal path. One of my main projects was the BAT VK5 SE preamp.
First I will say there are lots of good posts on this thread. They are very helpful, and are obviously from experienced members. Especially helpful are the experiments with power supply capacitors. I find they do make a positive difference, and are especially critical in SET amplifiers. SET amps are very sensitive to PS capacitors. Easy to ruin the sound with a polypropylene bypass. All polypropylene is a different story.
The stock BAT coupling caps are Jensen types, but with copper leads rather than silver leads found on the Jensen capacitors normally sold. This makes them quite a bit better than with silver leads. I have found this true on many, many types of capacitors used for signal. BAT has a reason for ordering them with copper leads, EVEN though they are cut off to 1/4"!
To make a long story a little shorter: the stock capacitors are hard to beat. Only the Duelund Alexanders, Aerovox, and some Russian capacitors were better in some ways. They also had the weight and tone in the lower range that all dry film capacitors lack. I have listened to just about all of those available except the Copper V-cap, and the Duelund Cast. The Duelund Cast will not fit without long leads and chassis modification.
I did not like the Tin foil V-caps, and this was after more than a week on a cable cooker, and another week or so on a tuner. But that's my experience. Many people like V-caps, but there are some who do not.
Without going into detail on interconnects, I would not recommend Nordost interconnects with the V-caps. I suggest Kubala-Sosna, Townshend Isolda XLRs, and MIT Oracle. These have worked excellent on the BAT preamp, both in stock form and after parts modifications. Final choice will involve the connecting component, as well as the BAT preamp.
