I am using the Cary 572SE's which use the Svetlana SV-572. They claim 20wpc but sound much more powerful. I really enjoy the sound of them. I have had all sorts of amps from ARC, Kora, Aronov, BAT, etc.. I think these have a similar sound to the BAT VK60 but maybe a bit warmer with better bass. Finding a preamp that matches is the harder part. I tried the AES/Cary AES-3 which is 6SN7 based and it had a lot of air but lacked something in the low end. I then tried the Cary SLP-50 which had better bass but lacked the open sound of the AES-3. The AES-3 was highly tweaked. I am now using an Audio Research LS-3 which is solid state and it very sweet sounding. I may have found a match.
One thing to mention is that the SV-572 tube is becoming more scarce. I stockpiled a bunch of them and I think that New Sensor has the rest. The 572SE amps can be modified by Cary to accept the 300B for approx. $750 including a set of Electro Harmonix 300B's. Sorry for all the history. The bottom line is that the Cary's have a nice sound.