Jim, as you realize but others commenting here may not, your BAT VK-200 does not provide RCA inputs. So the RCA-to-RCA cable you are asking about would have to be used with an adapter (or an unbalanced to balanced converter such as a Jensen Transformer), and the cable would be providing the signal to a balanced input.
For those reasons I would not necessarily expect the experiences others are basing their suggestions on to be applicable to your system. And personally I would consider using a Jensen Transformer in conjunction with RCA cables on its input side and short XLR cables on its output side to be the "right" way to implement this interconnection. Including cabling, that could be accomplished for close to your stated budget.
Also, seconding the comment by Wlutke just above you might want to take a look at what kind of 6C4 tubes are installed in your preamp. Trying different tubes would seem likely to be a more efficacious way of accomplishing the sonic changes you are looking for, especially given that 6C4’s appear to be relatively inexpensive. I found this statement in a 2003 thread at another forum:
Good luck. Regards,
-- Al
For those reasons I would not necessarily expect the experiences others are basing their suggestions on to be applicable to your system. And personally I would consider using a Jensen Transformer in conjunction with RCA cables on its input side and short XLR cables on its output side to be the "right" way to implement this interconnection. Including cabling, that could be accomplished for close to your stated budget.
Also, seconding the comment by Wlutke just above you might want to take a look at what kind of 6C4 tubes are installed in your preamp. Trying different tubes would seem likely to be a more efficacious way of accomplishing the sonic changes you are looking for, especially given that 6C4’s appear to be relatively inexpensive. I found this statement in a 2003 thread at another forum:
6C4 tubes are available from Watford Valves of England as the Mullard CV4058 (military number) which is also known as a KQDD/K or M8080. These tubes are the best 6C4 variant that money can buy, and Conrad-Johnson uses them in their new PV-14L audiophile preamp. They told me they have never found a better 6C4 tube. They were made for Britsh military mobile radios and can really take a thrashing, as well as a minimum 10,000 hour useful life.Finally, I see that the PV-14L is phase inverting, so if you already haven’t you may want to try interchanging the + and - connections to the speakers. That is likeliest to make a difference on recordings that were engineered with "purist" techniques, meaning a minimal number of microphones and minimal post-processing.
Good luck. Regards,
-- Al