Hi Macd, I think Mechans is on to something when he recommends an octal tube preamp. I have an all tube single ended system and when I switched out my pre that was using small "peanut tubes" to one that uses "octal" 6sn7's the tone was much richer and fuller. I have used three preamps that used small signal tubes in my system and they all sounded great but lacked a rich full tone, also I have owned two preamps that use octal tubes and both of them sounded much richer with a big tone. Just my observation with my system but something you should try, I think?
Good Luck, Tish
Good Luck, Tish