I used the Brimar 13D5 several years ago and loved them. In my SET, they were very clean and clear without being bright. I had the RCA clear tops prior and the Brimars were in another league in my opinion with quite noticeably more detail. Some have said they are a bit warm. I did not hear that at all but I did not hear any leanness either. Images were also more distinct. They are just a great tube, if your sonic preferences reflect the qualities mentioned.