I have tried the Siemens, Amperex and Mullards and can report that in my system there is no contest, the Mullards are by far the best sound. They are not at all tubby or bloated or rolled off on either extreme. This is not subtle. Now, all of the tubes are considerably better than the stock tubes. I am getting soundstaging which is magical. I thought the preamp was somewhat thin sounding until this tweak. As with all tube rolling, it will be system dependent. I can also say that Gary Dodd has experieced the same results. Just my 2 cents.